Code 25 - Knock Detection System
Ensure that intake manifold was tapped with steel object within 2" from knock sensor. If not, retest, then remove jumper wire from Self-Test Trigger.
- With ignition off, disconnect harness from knock sensor. Using 1 1/8" deep socket, loosen sensor and torque to 12-18 ft. lbs. (16-24 N.m). Do not overtighten. Go to next step.
- Disconnect MCU connector. Connect ohmmeter between engine ground and pin 13 in MCU connector. If resistance is less than 1000 ohms, repair circuit. If more than 1000 ohms, go to next step.
- Check continuity between pin 13 and knock sensor connector (Yel/Red). If less than 5 ohms, go to next step. If not, repair circuit.
- Check continuity between pin 14 and knock sensor connector (Blk/Lt Grn). If less than 5 ohms, go to next step. If not, repair circuit.
- Reconnect Self-Test Trigger jumper on Self-Test connector. Connect a 12v test lamp to battery positive terminal, then disconnect knock sensor. Perform steps 1) and 2) of Engine Running Test, then instead of tapping manifold with rod, tap test lamp to Yel/Red contact in knock sensor connector for 5 seconds. Observe voltmeter. If code 25 appears, replace MCU module. If any other code appears, replace knock sensor.