Checking the condition and replacing the knock sensor (Honda Civic 6)

Caution: Wait until the engine has cooled down completely before removing the oxygen sensor.

The knock sensor responds to increased engine vibration intensity, usually caused by detonation of the air-fuel mixture. Based on the information received from the sensor, the system adjusts the ignition timing, trying to maintain it at the highest possible level, which guarantees sufficient engine efficiency. The sensor generates an alternating current signal, the amplitude of which increases proportionally to the vibration level. To compensate for detonations, the ECM/PCM, if necessary, issues a command to shift the ignition timing towards retarding.

Knock sensors are not used on all models, but only on the following:

a) Civic with D16Y5 engine and CVT;
b) Civic with D16Y8 engine;
c) Integra with B18C1 and B18C5 engines.

Examination

1. Disconnect its electrical connector from the knock sensor and unscrew it from the engine (see accompanying illustration). Reconnect the connector to the sensor. This type of sensor is tested by recording voltage fluctuations on the voltmeter. Switch the device to the low voltage AC scale. Connect the negative probe of the meter to the sensor body, and the positive probe to the contact terminal. Lightly tap the bottom of the sensor with a hammer, simulating vibration. If the voltmeter does not register voltage fluctuations, the sensor should be replaced.

Note: In principle, this check can be performed without removing the sensor from the engine.

Replacement

1. The knock sensor is screwed into the cooling duct of the engine block (see illustration above) and its unscrewing is associated with certain losses of coolant, which can be avoided by emptying the block in advance (see Chapter Routine maintenance). Disconnect the electrical connector and unscrew the sensor from the engine.

2. New sensors are usually supplied with the threaded part coated with anti-seize sealant. Screw the replacement sensor into the regular place and tighten it to the required force. Connect the electrical wiring to the sensor and fill the cooling system (see Chapter Routine maintenance). Check the engine for signs of coolant leaks.