What to do if the Honda CRV knock sensor fails

Detect engine knocking to suppress the occurrence of knocking phenomena. When the engineer adjusts the knock sensor, the vibration pattern of the knock is written into the electronic control unit. If the knock sensor detects a vibration pattern, the ECU determines the engine knock and then delays the ignition advance angle.

Currently, advanced knock sensors can even tell which cylinder is knocking and delay the ignition advance angle of that cylinder separately. 

The knock sensor is mounted in the middle of the engine block. For example, a four-cylinder engine is installed between cylinders 2 and 3, or one between cylinders 1 and 2 and one between cylinders 3 and 4. It is used to measure engine shake and adjust the ignition advance angle in case of engine knocking.

Usually piezoelectric ceramics. When the engine vibrates, the ceramic inside is squeezed to produce an electrical signal. Because this electrical signal is very weak, the connecting wires of ordinary knock sensors are wrapped with shielded wires.

Knock sensors are AC signal generators, but they are very different from most other AC signal generators in cars. In addition to detecting the speed and position of rotating shafts like magnetoelectric crankshaft and camshaft position sensors, they also detect vibration or mechanical pressure. Unlike stators and magnetoresistors, they are typically piezoelectric devices.

They are made of special materials that can sense mechanical pressure or vibration (for example, when the engine starts knocking, it can generate alternating voltage).

Engine damage can occur due to premature ignition, poor exhaust gas recirculation, and engine knocking caused by low-quality fuel. The knock sensor provides a knock signal to the computer, prompting the computer to readjust the ignition timing to prevent further knocking. They actually act as "oxygen sensors" in the ignition timing feedback control loop.

The working principle of the knock sensor: when the engine vibrates or knocks the cylinder, the piezoelectric ceramic produces a voltage peak, and the greater the knock or vibration, the greater the peak. The engine control unit (ECU) processes the signals received by the detonation sensor, and if a detonation is determined, the ignition is postponed and the detonation continues.

When the engine control unit ECU does not receive the signal from the knock sensor, the ignition time is advanced to ensure the optimal output of the engine. Therefore, the purpose of using a knock sensor is to improve the dynamic performance of the engine without knocking.

The knock sensor is a sensor used to measure engine shake and adjust the ignition advance angle when the engine is detonation. This type of failure can occur when the engine ignites too early, has poor exhaust recirculation, or uses low-grade fuel, and can affect fuel consumption.

The knock sensor has a wire. When the engine detonation is abnormal, the piezoelectric element in the detonation sensor will be strongly vibrated or deformed, so that the piezoelectric element will generate a voltage signal and transmit it to the ECU of the car.

Hello, first of all, rule out whether the knock sensor is good, I have encountered one before, the body is bad, it will report this fault, check the body of each iron wire, I hope to help you [There is a problem with the car, ask the car master. 4S shop professional technician, 10 minutes to solve. 】

(1) Check whether the engine is obviously overheated, and if so, find out the cause first. (There are many related causes of engine overheating, pay attention to analysis).

2) Check if the engine knocks due to the failure of the ignition system.

If the ignition advance angle is too large, the mixture will burn too fast, resulting in engine knock combustion. The reasons for the excessive ignition advance angle are as follows: the crankshaft position sensor is installed in the wrong position (or loose), the timing belt is installed in the wrong tooth, the operation program of the power control module is faulty, the air intake detected by the air flow sensor is too small, and the detonation sensor is slow to respond.

3) Check if the pressure in the fuel system is too low.

If the pressure of the fuel system is too low, causing the mixture to be too thin, the combustion rate of the mixture will decrease, and the heat transferred through the cylinder wall to the coolant after the mixture is burned will increase, resulting in a high engine temperature. The engine temperature is too high, which is prone to detonation and combustion.

4) Check if the fuel is contaminated.

The lower the designation (i.e., octane number) of gasoline, the less resistant the gasoline is to knock off, and the more susceptible the engine is to detonation combustion when using this gasoline as fuel. In addition, if impurities are added to the gasoline with a relatively high grade, it will also cause the anti-knock ability of the gasoline to decrease.

5) Check whether the engine knocks due to the failure of the engine cooling system.

The actual working temperature of the engine is determined by the heat generated by the combustion of the mixture per unit time and the heat emitted by the heat dissipation system, if the cooling system is faulty, the former will be greater than the latter, the temperature of the engine will be higher and higher, and the tendency to detonation and combustion will be greater and greater.

6) Check if the pressure of the cylinder is too much.

If the pressure of the cylinder is too high, the combustion rate of the mixture increases, and the likelihood of detonation combustion in the engine increases. The reason for the excessive pressure of the cylinder is that the cylinder head, piston or cylinder gasket model is not the same as the working volume of the cylinder and the cylinder pressure.

7) Check whether there is too much carbon deposits in the combustion chamber of the engine.

If a large amount of carbon deposits accumulate in the cylinder, the hot spots formed by the carbon deposits may ignite the mixture in advance during the cylinder compression process, causing the pressure in the cylinder to suddenly increase during further compression, resulting in detonation and combustion. The causes of carbon deposition are as follows: the mixture is too concentrated, the ignition energy is relatively poor, the quality of gasoline is relatively poor, and the engine burns oil for some reason, etc., which can be checked separately.

8) Check if the EGR system is working properly.

If the exhaust gas recirculation system works within the working range, the system fails and cannot make the exhaust gas enter the cylinder to participate in the combustion, which will inevitably cause the combustion temperature of the mixture to rise, so that the engine will overheat and be prone to detonation combustion.

9) Check if the application and calorific value range of the spark plug are correct.

Yes, [If you have a problem with the car, ask the car master.] 4S shop professional technician, 10 minutes to solve. 】

Hello. Depending on the degree of badness. Probably not in the car. Pull out the plug with your finger and try [If you have a problem with the car, ask the car master. The first 4S store is dedicated to closing the industry technician, and it will be solved in 10 minutes. 】

When the control computer finds that the radar probe is working abnormally or damaged, it will cause the instrument to check the parking sensing system, so as to remind the driver to pay attention to the obstacles when parking and reversing, so as to prevent false alarms or no alarms resulting in collisions. You can first check whether the bumper is too dirty or the radar probe is obviously damaged, these situations are no problem, use the diagnostic instrument excitation and Zhaoqiao bridge radar control system to read the fault code, see which specific radar probe has a problem, replace the probe on the line, be sure to use the original parts, the quality of the analogues is very poor, and there will be a situation that the problem cannot be solved after replacement, the radar probe is positioned, there is a number on it, you need to tell the accessories which one is broken, In this way, the accurate model can be sent, otherwise if you change it wrongly, it will also show the fault of the same family.

Near the fan [If you have a problem with the car, ask the car master. 4S shop professional technician, 10 minutes to solve. 】