Knock sensor error (codes P0325, P0326, P0327, P0328)

During operation of the Tolyatti VAZ model with an electronic control unit, sometimes the “Check engine” signal lights up on the instrument panel. Translated from English it sounds like “Check engine”. The owner obeys the electronics and goes for diagnostics, where the technician tells him: “error p0327 has been detected.” This means that a low signal level is received from the knock sensor (DS). This problem can be caused by a broken motor, oxidation of the contact, or broken wiring. Next, we will tell you how to eliminate the defect and how to change the sensor.

general information

Error code p0327 is commonly referred to as “low knock sensor signal.” The defect is found on cars such as: VAZ, for example Grant, Niva or Priora, GAZ - GAZelle or UAZ - Patriot. If the system malfunctions, the voltage from the signal in the circuit does not exceed 0.5 V. At the same time, the “Check engine” icon may not light up, since this requires at least 2 drive cycles. That is, any pair of trips in which the engine temperature rises from cold, less than 49 °C, to acceptable operating temperature - above 71 °C.

Characteristic signs

Many motorists have encountered similar problems in their practice. It will not be difficult for them to determine if there are problems with the knock sensor.

The only problem is that with 0326 the symptoms will be approximately the same as with all other detonation errors.

This may appear as:

• unstable operation of the power unit at idle speed;
• a noticeable change in dynamics during acceleration towards a decrease;
• internal combustion engine detonation phenomena;
• transition of the ECU to emergency operation mode.

If the unit detects such an error, the check engine light (Check or Check Engine) lights up on the dashboard.

But for such an error to occur, it is necessary to create the appropriate conditions.

How does DD work?

The knock sensor is a piezoelectric element - an electromechanical converter that interacts with the electronic engine control unit (ECU). While the engine is running, the DD adjusts the ignition timing, since fuel detonates differently from different octane numbers.

For reference. Error P0327 is often accompanied by other trouble codes: P0325, P0326, and P0328. All of them are connected to the knock sensor.

Error P0325

Error code P0325 is called “malfunction in the knock sensor circuit.” In English it sounds like: Knock Sensor 1 Circuit Malfunction. It signals to the driver that the engine control unit does not receive a signal from the DD. Due to the fact that some problems have arisen in its power supply or signal circuit. The cause of this error may be very low or very high voltage coming from the sensor due to a break or poor contact in the wiring harness block.

Possible causes of the error

There are several reasons why error p0325 may occur. Among them:

• broken knock sensor wiring;
• short circuit in the DD wiring circuit;
• malfunction in the connector (chip) and/or contact DD;
• high level of interference from the ignition system;
• malfunction of the knock sensor itself;
• malfunction of the engine control unit (abbreviated as ECM).

Conditions for recording error code 0325

The code is installed in the ECU memory on a warm engine at a crankshaft speed of 1600-5000 rpm. if the problem does not go away within 5 seconds. and more. The archive of fault error codes itself is cleared after 40 consecutive cycles without fixing a fault.

To find out exactly what problem caused the error, additional diagnostics must be performed.

External symptoms of error P0325

External signs of this error may include the following situations. However, they can also indicate other errors, so you should always perform additional diagnostics using an electronic scanner.

• The Check Engine light on the dashboard is activated;
• the engine control unit operates in emergency mode;
• in some cases, engine detonation is possible;
• loss of engine power is possible (the car “does not pull”, loses its dynamic characteristics, accelerates poorly);
• Unstable engine operation at idle.

In general, the symptoms of failure of the knock sensor or its wiring are outwardly similar to those when the ignition is set late in the car (on carburetor engines).

Error diagnosis algorithm

To diagnose error p0325, you must have an electronic OBD-II error scanner (for example Scan Tool Pro Black Edition ). It has a number of advantages over other analogues.

32-bit Scan Tool Pro Black

allows you to scan engine blocks, gearboxes, transmissions, auxiliary systems ABS, ESP in real time and save the received data, as well as make parameter changes.
Compatible with many cars. Can be connected to a smartphone and laptop via Wi-Fi or Bluetooth. Has the greatest functionality in the most popular diagnostic applications. By reading errors and monitoring sensor readings, you can determine malfunctions of any of the systems. The error detection algorithm will be as follows:

• First, you need to make sure that the alarm was not false. To do this, you need to reset the error using the scanner (if there are no others, otherwise you need to deal with them first) and perform a test drive. If error p0325 occurs again, then we continue further.
• You need to check the functionality of the knock sensor. This can be done in two ways - using a multimeter and mechanically. Using a multimeter, you first need to measure the voltage of the sensor when pressure is applied to it. And also check its circuit to the ECU for an open circuit. The second, simpler method is to simply hit the engine at idle speed in the immediate vicinity of the sensor. If it is working properly, then the engine speed will drop (the electronics will automatically change the ignition angle), which is true that this algorithm does not work on all cars and in some cases, reading the BC signal from the DD works under other additional conditions).
• Check ECM functionality. In rare cases, the program may crash. It is unlikely that you will be able to perform the check yourself, so it is better to seek help from an official dealer of your car manufacturer.

How to get rid of error p0325

Depending on what exactly caused the p0325 error, several options are possible to solve this problem. Among them:

• cleaning contacts or replacing wiring connectors (chips);
• repair or replacement of wiring from the knock sensor to the engine control unit;
• replacing the knock sensor itself, most often this is what is done (this unit cannot be repaired);
• flashing or replacing the engine control unit.

Error p0325 itself is not critical, and the car can get to a car service center or garage under its own power. However, there is a risk that if detonation occurs in the engine, the ECU will not be able to react properly and eliminate it. And since detonation is very dangerous for the power unit, you need to get rid of the error and carry out the appropriate repair work as quickly as possible after its occurrence.

How is it diagnosed?

The operating principle of injection engines is practically the same for all cars. The control unit, which receives information from several controllers, is responsible for the balanced interaction of the components and assemblies of the motor. The knock sensor is one of them, and if it breaks, the engine runs intermittently. For example, let’s look at the method for determining error p0327 on the VAZ Priora ECU. To do this you need:

• warm up the engine to a temperature of 60 °C;
• set the crankshaft speed to 1300 rpm.

Next, you will need to connect the adapter cable to the diagnostic connector and take readings. In this case, the car must do at least 2 drive cycles in advance.

Nuances of self-diagnosis of the VAZ 2114

When carrying out diagnostics at specialized service stations or independently, various results and error codes can be obtained. Not all drivers know that faults can be identified without an on-board computer. An odometer is used for this. A significant drawback of such diagnostics is the addition of error numbers into a single sum. For example, if an error of 8 and 1 occurs, the odometer will display the number 9. The device's memory is not automatically cleared, so error codes will be displayed until manually reset by disconnecting the battery terminals for a few seconds.

Resetting the "checkengine" error

As you can see from the video, the error can be reset by following these steps:

• Turn off the engine, but leave the car's ignition on.
• Disconnect the car battery terminal and wait a few seconds.
• Reinstall the terminal and start the engine.

The error will be reset after these steps, but if it is caused by serious malfunctions in the engine, it will occur again. In this case, the best option would be to contact a service station.

Reasons for the failure

If error code 0327 is registered in the ECU, you should first reset it and operate the car again. Perhaps it was a simple glitch. If it appears again, you should:

• check the mounting of the block on the sensor;
• inspect the wires for breaks;
• inspect the power circuit to identify a short circuit;
• check the sensor with a multimeter up to 200 mV.

Sometimes error code p0327 appears due to poor contact between the motor and the engine block. Soot or rust appears on the mating surface, which deteriorates the quality of the transmitted signal.

Diagnostic features

Diagnostics begins with checking that the error is not the result of a false alarm by the system. This happens sometimes, and after this problem occurs there are no real problems with the engine, fuel system or knock sensor.

Carrying out such a diagnosis is quite simple. To do this, the error code is first erased from memory according to the instructions provided for each vehicle. Recommendations can be found in the operating instructions.

Having reset the error, the driver performs a test drive. In this case, you need to create all the conditions described above under which such a code appears in the ECU. Warm up the engine, raise the speed to the desired level.

If the error appears again, it means there is some kind of problem, a provoking factor.

Further diagnostics involves the implementation of such mandatory measures.

• Turn off the ignition on the car. Locate the ECU and the wire that goes to the knock sensor. They need to be separated for a while.
• Take a multimeter. The most common one is suitable for garage use. You don't have to buy an expensive model. Using a test instrument, the wires connecting the control unit and the controller are checked for integrity. This procedure is called dialing.
• Now check how well and tightly the wires of the sensor and the ECU are connected to each other. If you see traces of corrosion or oxides, you need to clean them. This can be done with fine-grained sandpaper. Just make sure the car's power is turned off. To do this, simply disconnect the negative terminal from the battery.
• If everything is fine with the wires, there are no signs of damage, the contacts are intact, then the tightening torque on the seat of the detonation controller is also checked.
• When replacing or installing, it is extremely important to tighten the sensor in accordance with the manufacturer's recommendations. This should not be done with your hands or regular wrenches, but with a torque wrench. It is important to observe a certain regulated tightening torque.
• It often happens that the sensor is simply not fully tightened. If over-tightened, mechanical damage occurs and the controller must be completely replaced.
• Each specific vehicle has its own recommendations for the tightening torque used. But on average it is from 20 to 25 Nm in relation to passenger cars.

How to change a knock sensor

The process of replacing DD with VAZ 2114–2115, 2110–2112, as well as Priora, Grant and Kalina, is quite similar. For all of the listed cars, the knock sensor is located on the outside of the cylinder block, under the 2nd and 3rd spark plugs. Here are the step-by-step instructions:

1. Disconnect the battery.
2. Disconnect the power supply.
3. Unscrew the DD fastening bolt (socket wrench 13 mm).
4. We clean the mating surface on the block with fine sandpaper and degrease it with gasoline.
5. Screw in the sensor and tighten the bolt to a torque (10–25 N×m).
6. We connect the power supply.

Then we connect the battery. Using a diagnostic scanner or mobile application, we remove the error.

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What to do if the problem recurs

If you replaced the knock sensor and deregistered p0327 in the ECU, and the “Check engine” icon appears again, then the problem may be in the engine sensor itself. It needs to be checked. You will need a multimeter, which should be set to resistance measurement mode (ohmmeter). The minimum threshold value is 5 MΩ (operating alternating voltage: U= 0.5–3 V). If it shows below, then the sensor is defective. It is unprofitable to repair it, since a new one costs about 250 rubles.

Another reason: the DD is attached to the cylinder block with a bolt. But its crimping force is small, so the detonation signal is weak. Experts recommend using a pin instead of a bolt, and tightening the sensor with a nut. Then the risk of error p0327 is sharply reduced. In addition, you should make sure that the formation of a malfunction is not caused by: extraneous knocks, such as vibration of the pan protection or the clatter of hydraulic compensators, as well as poor-quality fuel or poor fastening of the engine to the cylinder block.

On a note. Experts recommend buying one of two brands of knock sensors. First original: AvtoVAZ number 21120–3855020–03–0. Second analogue: Bosch - 0 261 231 046.

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Fixing breakdowns

After the diagnostic procedure, and determining why the VAZ Kalina 8 valves are capricious, it is necessary to completely check the entire line of the unit, which is indicated by the decoding of the index. This must be done by testing the main line and replacing the blocks with known good ones. Additionally, the specifics of operation should be taken into account - due to constant shaking on broken roads, the standard terminals can become loose, which provokes a breakdown in contact. In this case, the computer will also indicate the presence of a malfunction. In order to prevent this, experienced craftsmen recommend treating connectors with special impregnations that repel water and carry out preventive maintenance in a timely manner.