How to check and replace the camshaft sensor in a car

Every modern car has a camshaft position sensor. It is a very important part of any vehicle as it helps ensure that the engine runs properly. The camshaft position sensor is built next to the engine just under the hood. Typically, different car manufacturers and brands have their own unique location for mounting the sensor near the engine. You can find it either at the back of the cylinder head or near the engine.

In this article we will look at DPRV. Many people confuse it with the crankshaft position sensor because they are very similar. But you must understand the difference, because they perform different functions in the car and have different symptoms and causes of problems.

What is a camshaft position sensor

The camshaft position sensor is also called the cylinder sensor or camshaft sensor. In sequential fuel injection systems, the electronic control unit must determine which cylinder should be injected next. This information affects engine operation and comes from the DPRV. As the engine rotates, the DPRV sends a signal to the on-board computer whenever a particular cylinder is at top dead center (TDC). Thus, the duration of pulse injection is estimated, for which the camshaft sensor is responsible.

In simultaneous fuel injection systems, the on-board computer is not used to determine the cylinder and injection order, since this is not necessary for the operation of the system. When a signal is received from the crankshaft or distributor, the exact cylinder is determined by recognizing the mechanical positions of the crankshaft, camshaft and valves.

Types of sensors used

The most popular are 2 types of DPRV, which look almost the same and differ slightly in design:

inductive;
Hall Sensor.

An inductive sensor is needed to register the cylinder and can be located inside the camshaft. Therefore, a device with a magnet is mounted near it. Each time a magnet passes through the DPRV, its magnetic field changes and the resulting pulse is sent to the on-board computer for subsequent processing.

The Hall sensor may be located inside the camshaft. A screen with a socket and a magnet is installed on the shaft. When the screen passes between the magnet and the hall sensor, the DPRV turns on and off. While the socket is in front of the DPRV, the voltage returns to the amplifier through the third signal cable. As long as there is a solid sector of the screen in front of the sensor, the feedback voltage is interrupted as the magnetic field disappears.

Where is the sensor located

The location of the DPRV varies depending on the make of the car. In most cases, you can find it in the following places:

near the cylinder head;
near the wiring connectors on the front of the motor;
near the toothed belt mount;
on the rear side of the cylinder head;
special compartment under the hood;
inside the cylinder head.

First, consult your vehicle's manufacturer's repair manual. This contains all the necessary information.

How to remove the camshaft sensor

On cars with a transversely mounted 16-valve engine, access to the DPRV occurs in two ways. Through a hole in the body located under the plastic fender liner or through the hood. In the first case, it is necessary to lift the side of the front of the car where the sensor is located. When the wheel lowers, unscrew the self-tapping screws securing the fender liner and remove the protection, then remove the sensor. If you decide to remove it through the hood, you need to remove the protection from the camshaft gears, this will provide access to the sensor.

Working principle of the camshaft position sensor

The task of the DPRV is to work with the crankshaft sensor to determine the exact position of its drive. Thanks to the combination of both sensor signals, the engine control unit knows when the first cylinder is at top dead center.

This information is needed for 3 purposes:

To start fuel delivery during sequential injection.
To activate the solenoid valve signal for the pump injection system.
To control cylinder detonation.

The DPRV operates in accordance with the Hall principle. It scans the ring gear on the camshaft. Rotation of the ring gear changes the Hall voltage IC in the DPRV housing. This voltage change is transmitted to the control unit and evaluated there in order to set the required data.

Replacing the sensor

Replacing a faulty sensor usually does not cause problems. It is installed on one (rarely two) bolts.

You can remove and change the sensor yourself. For dismantling and installation, only a 10 key is required. Usually the sensor is located in an accessible place.

When purchasing a new sensor, you should take the faulty sensor with you. It is required to check the sensor mounting depth. It must match exactly so that the new sensor does not break at the first start.

When buying a Chinese sensor, there is a possibility of getting a “dummy”, so it’s a good idea to take a multimeter with you when purchasing. No seller will replace a sensor installed for a couple of minutes.

Problems that a faulty camshaft sensor can create

The camshaft's job is to control the consumption of gasoline and the emission of vapors from the exhaust system. Compensation vanes are installed on the camshaft, which control the exhaust and intake valves. The timing belt and chain connect the camshaft to the crankshaft. The vehicle's engine control unit monitors the rotating position of the camshaft using a component called a "camshaft position sensor." Based on the information transmitted by the DPRV, the engine control unit will determine how much fuel should be introduced into the combustion chamber. There are many symptoms of a bad camshaft sensor in your car.

Ignition problems – The mixture of air and fuel in an internal combustion engine requires a spark to ignite. In some vehicles, if the DPRV fails, there will be no spark, which is the first sign of a DPRV malfunction. If you can't create a spark, then you can't start the engine. Unfortunately, it is quite difficult to determine the source of the malfunction, especially if it is a DPRV. But don't be surprised that it might be him.

Reduced Power – If the DPRV fails in a vehicle with an automatic transmission, you may experience a transmission lock-up fault. The only thing you can do is turn off the engine, wait a few seconds and start it again. This is just a temporary solution that allows you to quickly deliver your car to the nearest auto store. If you do not replace the DPRV, the gear shifting problem will definitely return.

Poor engine performance - a faulty DPRV will lead to incorrect fuel injection into the cylinder chamber. Since the engine depends on the correct mixture of air and fuel, problems will immediately arise in its operation. When you press the gas pedal, the acceleration of the car will be significantly less. You probably won't be able to go faster than 50-70 km. at one o'clock. Moreover, the car may begin to move jerkily.

Poor Fuel Efficiency – The fuel injectors will send too much gasoline into the combustion chamber if you have a bad fuel pressure sensor. At the same time, fuel consumption increases significantly, which can be noticed after the first 50 km. The breakdown is eliminated by replacing the DPRV.

How can a sensor fail?

Like every part or component in your vehicle, the sensor will eventually stop working when it reaches the end of its life because an internal part, wire, or associated component has failed.
The symptoms your engine may experience at this point may vary depending on the type of sensor failure: for example, the problem is with the circuit, the connector, the sensor itself, or a related component. Once your vehicle's computer detects a faulty sensor, it will turn on a check engine light and store a diagnostic trouble code (DTC) in its memory (see table below for common camshaft position sensor trouble codes).

Possible causes of malfunction

DPRV is a pulse generator that creates a very weak signal. There is a small chance that the current will gradually weaken the integrity of its winding. However, vibrations caused by magnetism travel through the gear teeth. When the camshaft is turned, the force changes just like the signal generated. These vibrations cause microscopic movements within the DRV, creating weak points in essential parts, especially the winding in the case of inductive type DRV.

With a Hall-type sensor it is a completely different story. This type of DPRV is a solid-state device, that is, its electronic component, such as a diode or transistor. Voltage can damage the sensitive parts of the DPVR. Short circuits and incorrect connections can also damage it. And remember that you need a polarity sensitive power supply.

How to check the camshaft position sensor

When troubleshooting a suspected DPRV fault, you should follow the diagnostic guidelines in the vehicle manufacturer's literature to isolate the faulty component when a DTC is present. There is no other way to know what is causing the problem (spark, bad ignition module, coil, computer, bad wiring or ignition switch).

Magnetic DPRVs can be checked by disconnecting the electrical connector and checking the resistance between the terminals. For example, on a GM 2.3L Quad 4, the sensor should show a voltage between 500 and 900 ohms. When testing DPRV, always take into account the technical specifications of the vehicle manufacturers. Obviously, if you see zero resistance (short circuit) or infinite (open) resistance, this means that the DPRV is not working and needs to be replaced.

Do-it-yourself troubleshooting

An operational problem should prompt a system check. You can do it yourself in a relatively short time. If you are a novice driver or do not understand the intricacies, the best solution would be to contact a professional service center. There, the specialists will help eliminate all problems and breakdowns of the mechanism.

The crankshaft and camshaft sensors are diagnosed using a special tester. The cables are connected to the required terminal (A, B) in the appropriate order. The car starts, you should wait until it stops

It is important to carefully monitor changes in voltage

In the first ten seconds, the voltage value should be equal to the on-board type value. In this case, the chain is not broken. If this does not happen, then it is closed or broken.

Sometimes there is no voltage when the circuit is intact. Such malfunctions often occur due to the fault of the controller. This is easy to check by connecting terminals A and C to the tester. As a result, there should be on-board voltage when the ignition is on. If this does not happen, then you need to look for a break further.

Testing a two-wire inductive sensor

There are a number of common signs of a faulty DPRV. If you have these problems, you may need to replace it. These same symptoms can be caused by problems with the ignition or fuel injection systems. Thus, before replacing the DPRV, it is worth conducting tests to determine the real source of the malfunction.

If the check light comes on, your ECU is recording a trouble code. You can check for errors using a special diagnostic tool. Codes between P0335 and P0338 correspond to DPR problems.

This is probably the easiest and most accurate way to test and determine the problem of the DPRV. Unfortunately, the DPRV, as a rule, fails much earlier than the corresponding indicator lights up. To be constantly aware of the car's problems, it is worth conducting other types of testing.

RPM is the next method for checking the DPRV, which also requires a diagnostic tool. One of the scanner settings allows you to read the engine speed in revolutions per minute (RPM). Set up the scan tool to read engine speed and start it. The scan tool should read between 100 and 500 rpm. A low value indicates that the DPRV is not working properly. “0” means that the DPRV is completely out of order.

Multimeter testing

Of course, not everyone has access to a scanner (although they can sometimes be rented from parts stores). A multimeter is a more common and very useful tool for diagnosing many of your vehicle's electronic components. The multimeter can measure voltage, current and resistance.

You can remove the DPRV and then check the resistance. Attach one end of the multimeter to each DPRV wire. A resistance of 0 means there is a short circuit. Infinite resistance means there is an open circuit. Any of these readings indicate that the DPRV is not working. For any other value, check the manufacturer's instructions. If the reading does not match the recommended resistance, you must replace the DPRV.

Another way to check the DPRV using a multimeter is to check the output voltage using a motor. To do this, you will need an assistant. Strip the connectors and measure the output voltage in AC millivolts. Typically, this reading is about 200 millivolts, but may vary depending on the brand of car. Check the specifications in the user manual. If there is no output voltage, then obviously your sensor is not working properly.

These tests will help you determine the source of the problem. They will either prevent repairs you don't need or confirm that the repairs you are about to make are the ones you actually need. If testing really confirms that your DPRV is faulty, you will have to replace it.

Troubleshooting DPRV

If the Check Engine indicator on the panel has already come on (it may not be lit constantly, but may appear periodically), you just need to read the fault code using a diagnostic device. If you do not have such a device and it is impossible to buy it, you need to contact a specialist.

After receiving the exact fault code and decoding it, we recommend performing several simple tests. The presence of one of the above DPRV fault codes does not always indicate that the sensor must be replaced. Sometimes the source of the problem is damage to the wiring, connector, etc. It is quite possible to fix such problems on your own.

But to check the functionality of the camshaft position sensor itself, you need to perform several steps. Of course, it is difficult to check the signal without special equipment. But checking the camshaft sensor with a multimeter will provide basic information.

First, visually check the condition of the sensor connector and the wires that go to it. Make sure there is no dirt, oil or rust that could cause problems. Check the wires for damage. Sometimes problems are caused by broken wires, poor connections, or defects in the insulating layer caused by exposure to elevated temperatures. The DPRV wires should not come into contact with the high-voltage wires of the ignition system.

This is interesting: Intake manifold VAZ 2114: characteristics, replacing the gasket yourself

After that, we pick up a digital multimeter; it “knows how” to check the value of alternating and direct current (AC and DC, respectively). But you need to obtain information in advance about what these indicators should be for the sensor used on your car.

Some sensors have connectors designed so that you can connect additional wires to them to read data with a multimeter.

If this is not possible, try disconnecting the DPRV connector and connecting thin copper wires to each terminal of the connector. After this, install the connector in place so that two wires protrude from its body.

Another option is to pierce each of the wires with a needle or pin (do everything carefully so as not to short the wires!). After such a diagnosis, damaged areas of insulation should be well wrapped with electrical tape to prevent moisture from getting inside.

Checking the camshaft sensor with a multimeter

To check the DPRV, dismantling is necessary. This is not difficult to do; you just need to disconnect the contact group of wires from it and unscrew the fastening bolt. You will also need a small metal object (ferrous metal so that it is magnetic) to test.

The algorithm for checking the sensor with a multimeter is as follows:

Take a multimeter and switch it to the DC voltage measurement mode in the range up to 20 V (depending on the specific multimeter model).
Disconnect the “chip” from the sensor by unclipping the latch.
Remove the sensor from its mounting location.
On the “chip” of the sensor 21110-3706040 of a VAZ car (and on many others), contact “A” corresponds to ground, contact “C” is the positive wire, comes from the control relay, contact “B” is the signal wire (middle). For sensor chip 21120-3706040, contact “A” corresponds to ground, contact “B” is the positive wire from the control relay, contact “C” is the signal wire.
Check the presence of power on the chips. To do this, you need to turn on the ignition on the car (but do not start the engine) and do this with a multimeter. If there is no power to the chips, then you need to look for the reason. This could be faulty wiring (insulation damage, broken wires), failure of the control relay, or a glitch in the electronic control system (ECU).
Next, you need to connect the sensors for testing according to the diagrams shown in the figure.
Apply a voltage of 13.5±0.5V to the sensor (although less is allowed, for example, 12...12.5 Volts from the battery).
If, when power is applied to the sensor, the voltmeter detects a lack of voltage on the sensor, then this indicates either a breakdown of the sensor itself, the test can be completed and you can prepare to replace the sensor with a new one.
Measure the voltage between the positive and signal contacts. It must be equal to at least 90% of the supply voltage (that is, if the supply voltage is 12 Volts, then the voltage at the signal contact must be at least 10.8 Volts).
Bring a metal object prepared in advance to the end of the sensor (its signal part). Re-measure the voltage at the signal contact. It should be no more than 0.4 Volts. Remove the plate - the voltage value should be restored to 90...100% of the supply. If there are any deviations during the verification process, it means that the sensor has failed and must be replaced.

Please note that it is advisable to check not only sensors already installed on the engine, but also newly purchased ones, since there is always a risk of purchasing a defective product.

Checking the 2-wire camshaft position sensor

If your car uses an electromagnetic DPRV, switch the multimeter to AC mode.
Another person must turn the ignition on by turning the key in the lock without starting the engine.
Voltage should appear in the circuit. Connect one of the multimeter probes to ground (any metal component of the engine), and connect the second one in turn to the camshaft sensor wires. The absence of current on all wires indicates a problem in the wiring that goes to the sensor.
Ask the person in the car to start the engine.
Touch one multimeter probe to one wire of the DPRV connector, and the other to the other. Values will appear on the device screen, which should be compared with the operating readings given in the car’s operating instructions. As a rule, the readings on the screen vary within 0.3-1 volts.
The absence of a signal indicates a malfunction of the camshaft sensor.

This is interesting: Replacing the main brake cylinder on a VAZ-2110: checking, repairing the GTZ

Three-wire camshaft sensor testing

Identify the power, ground and signal wires (use the repair instructions), and then check the integrity of the wiring that goes to the sensor. The multimeter must be switched to DC mode.
Another person must turn on the ignition without starting the engine.
We connect the black probe of the multimeter to “ground” (any metal part of the engine), and the red probe to the power supply wire of the DPRV. The results obtained should be compared with the data in the operating instructions.
An assistant must start the engine.
Touch the red probe of the multimeter to the signal wire of the DPRV, and connect the black probe to the ground wire. If the sensor malfunctions, the voltage will be lower than stated in the repair manual. Sometimes the multimeter does not show anything at all, which also indicates a sensor failure.
Remove the DPRV and check the element for mechanical damage or contamination.

Below is a video that clearly demonstrates how you can conduct such tests. In some cases, the electrical circuit is working properly, and the sensor also gives correct readings during tests. The question arises: why do errors and problems appear in engine operation? Sometimes the causes are related to other engine components. Errors may appear due to a loose timing belt or a faulty tensioner. Because of this, the DPRV will transmit the wrong signal.

Checking the DPRV using an oscilloscope

An electronic oscilloscope helps to understand how the camshaft position sensor works and whether it produces pulses at all. Usually they use a so-called electronic oscilloscope, that is, simply a simulator program installed on a laptop or other similar device. You need to connect to the camshaft sensor and take an oscillogram from it. Ideally, there should be a smooth comb diagram with one drop-out peak that corresponds to the rapper passing through the sensor. If the oscillogram has a different shape, additional verification is needed.

When diagnosing the camshaft sensor of Nissan cars (in particular, Nissan Almera) with an oscilloscope, the shape of the oscillogram will be different. It will not be smooth, but in the form of 3 impulses, then a space, then 4 impulses - a space, 2 impulses - a space and one impulse - a space. For engines from this automaker, this feature is the norm.

Checking three-wire DPRV

Steps to test a three-wire DPRV:

remove the air filter cover;
disconnect the 3-pin connector in the DPRV;
turn on the ignition;
using a multimeter and cables from the kit, measure the voltage between terminals 1 and 3 of the sensor connector;
recommended value: 4.5 to 5.5 V;
turn off the ignition;
check the wires between the test box and the 3-pin open circuit connector;
Recommended wire resistance: max. 1.5 Ohm;
check the wires for short circuit, to battery (+) and ground (GND);
If the wires and voltage are ok, replace the camshaft position (CMP) sensor.

Engines 1.8L:

IMPORTANT! Before starting any test, the battery voltage must be at least 11.5 volts.

disconnect the 3-pin camshaft position sensor connector;
switch DMM to voltage measurement position;
connect the DMM between the external terminals of the connector;
Switch the ignition to the “ON” position, but do not start the engine. You should see a minimum of 4.5 volts;
Now turn the ignition “OFF”;
connect the VAG 1598/22 test unit to the ECM connector;
Check the wiring between the test block and the ECM connector using the wiring diagram. Checks must be performed on each of the following points:

Wire 1 and socket 11.
Wire 2 and socket 76.
Wire 3 and socket 67.

For each of the above tests, the maximum resistance should not exceed 1.5 ohms.
Check all wires for short circuits.
when connected and there is voltage between terminals 1 and 3, replace the camshaft position sensor.
If the wiring is OK but there is no voltage between terminals 1 and 3, replace the ECM.

2.8L engines:

IMPORTANT! Before starting any test, the battery voltage must be at least 11.5 volts.

disconnect the 3-pin wire connectors from the camshaft position (CMP) sensors;
connect the DMM to measure voltage on terminals 1 (+) and 3 (ground) of the CMP connector using the adapters from the test kit;
turn the ignition to the “ON” position, but DO NOT start the engine;
Measure the voltage between terminals 1 and 3. It should be a minimum of 9.0 volts;
turn the ignition “OFF”;
connect the test block to the ECM connector;
Check the wiring for open circuit between the ECM and the 3-pin connector according to the wiring diagram;
For the CMP sensor connector on the right cylinder head, measure the following:

Connector 1 with ECM connector 11.
Connection terminal 2 to ECM76 connector.
Connector 3 with ECM 67 socket.

maximum resistance should not exceed 1.5 Ohms;
For the CMP sensor on the left cylinder head, measure the following:

Connector 1 with ECM connector 11.
Connector 2 with ECM 44.
Connector 3 with ECM 14.

for each of these tests the maximum resistance is 1.5 ohms;
If the wiring and voltage at terminals 1 and 3 are OK, replace the camshaft position sensor;
If the wiring is OK but there is still no voltage at terminals 1 and 3, replace the ECM.

Functional test of the CMP sensor:

To perform a functional test of the camshaft position sensor, disconnect the 4-pin connector from the ignition coil and check the DTC memory;
check the supply voltage of the camshaft position sensor and make sure that it is in order;
move away the rubber connector of the CMP sensor (the sensor remains connected);
connect a voltage tester between terminals 1 (+) and 2 (phase);
start the engine for a few seconds;
for every second engine revolution, the voltage tester should flash briefly;
if the voltage indicator does not blink, turn off the ignition and disconnect the 3-pin connector from the camshaft position sensor;
connect the test block to the ECM connector;
Check the signal wire for continuity between terminal 2 and socket B2. The maximum resistance should not be more than 1 ohm;
If the specified value is not obtained, check for a short or open circuit in the wiring between the CMP sensor connector and the ECM;
if the wiring is ok, connect the DMM between the B2 test block socket and ground;
turn the ignition key to the “ON” position. Must be at least 4.0 volts;
if the specified value is not obtained, replace the ECM;
If a value is obtained, replace the camshaft position (CMP) sensor.

Results

At the beginning of the article, we mentioned the unpleasant consequences that can result from a breakdown of the DPRV. If you find at least one of the signs of a malfunction of the camshaft position sensor, we advise you to diagnose the problem as quickly as possible. Otherwise, you might just end up standing in the middle of the road. Start by reading the fault codes stored in the ECU memory and, if necessary, check the sensor itself. Now you already know how to do this using a regular digital multimeter. Very often you can solve the problem yourself without spending extra money on diagnostics and replacement.