Faulty Signal. Permanent Fault

Disconnecting Knock Sensors
To access knock sensor (KS) connectors, remove the following:

- Remove dip stick bracket at the rear edge of the engine, turn dip stick.
- Reinstall after fault-tracing.
- Proceed to: Checking Ground Lead section below.





Checking Ground Lead
- Ignition OFF.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Disconnect knock sensor.
- Connect an ohmmeter between knock sensor connector terminal 2 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Proceed to: Checking Signal Cable section below.

If reading is incorrect:
^ Proceed to: Checking ECM Connector section below.





Checking ECM Connector
- Ignition OFF.
- Knock sensor disconnected.
- Check engine control module (ECM) connector for contact resistance and oxidation and remedy.
- Engine control module connected.
- Connect an ohmmeter between knock sensor connector terminal 2 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ The cause of the diagnostic trouble code (DTC) has been loose connections in the engine control module connector.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Check cable between knock sensor connector terminal 2 and engine control module # A17 for an open-circuit.
^ Proceed to: Verification section below.





Checking Signal Cable
- Ignition OFF.
- Knock sensor disconnected.
- Connect an ohmmeter between knock sensor connector terminal 1 and ground.
- The ohmmeter should read approx. 1 M ohms.

If reading is OK:
^ Proceed to: Checking Knock Sensor Signal section below.

If value is lower:
^ Check cable between knock sensor terminal 1 and engine control module # A2 (EFI-143) or # A30 (EFI-433) for a short-circuit to ground.
^ Proceed to: Verification section below.

If value is higher:
^ Proceed to: Checking ECM Connector section below.





Checking ECM Connector
- Ignition OFF.
- Knock sensor disconnected.
- Check engine control module connector for contact resistance and oxidation and remedy.
- Engine control module connected.
- Connect an ohmmeter between knock sensor connector terminal 1 and ground.
- The ohmmeter should read approx. 1 M ohms.

If reading is OK:
^ The cause of the diagnostic trouble code has been loose connections in the engine control module connector.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Check cable between knock sensor terminal 1 and engine control module # A2 (EFI-143) or # A30 (EFI-433) for an open-circuit.
^ Proceed to: Verification section below.





Checking Knock Sensor Signal
- Ignition OFF.
- Connect the knock sensor.
- Start engine and run to normal operating temperature.
- Go into scrolling values.
- Rev engine to 3500 rpm.
- Read off the knock sensor signal value.
- This value should be 2 - 6 at engine speeds (RPM) above 3500 rpm.

If reading is OK:
^ The diagnostic trouble code has been caused by loose connections in the knock sensor connector.
^ Check connector for contact resistance and oxidation and remedy.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Try a new knock sensor.
^ Proceed to: Verification section below.





Verification
After carrying out the repair, check that the fault has been remedied as follows:

- Ignition OFF.
- Reconnect connectors, reinstall components etc.
- Start engine and run to normal operating temperature.
- Go into scrolling values.
- Rev engine to 3500 rpm.
- Read off the knock sensor value.
- This value should be 2 - 6 at engine speeds above 3,000 rpm.

If reading is OK:
^ Fault corrected.

If reading is incorrect:
^ Proceed to: Fault-tracing Information section below.

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected

No:
^ Proceed to: Disconnecting Knock Sensors section above.