For 1990-2009 cars

### Circuit Description

The knock sensor (KS) produces an AC voltage at all engine speeds and loads. The powertrain control module (PCM) then adjusts the spark timing based on the amplitude and frequency of the KS signal. The PCM uses the KS signal to calculate the average voltage. Then the PCM assigns a voltage value. The PCM checks the KS and related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should stay outside the assigned voltage range. This DTC will set if the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system.

### Conditions for Running the DTC

• | DTCs P0117, P0118, P0122, P0123, or P0327 are not set.

• | The engine run time is more than 20 seconds.

• | The engine coolant temperature (ECT) is more than 70°C (158°F).

• | The engine speed is between 1,800-6,400 RPM.

• | The manifold absolute pressure (MAP) is more than 60 kPa.

### Conditions for Setting the DTC

The PCM detects a malfunction in the KS diagnostic circuitry that will not allow proper diagnosis of the KS system.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | Use the scan tool in order to clear the DTCs.

### Diagnostic Aids

• | The KS must be torqued correctly to 25 N·m (18 lb ft).

• | The mounting between the sensor and the engine must be free of burrs, casting flash, and foreign material.

• | The KS head must be clear of the hoses, the brackets, and the engine electrical wiring.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 | Important: If you can hear an engine knock, repair the engine mechanical problem before proceeding with this diagnostic.

1. Observe the Freeze Frame/Failure Records data for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close as possible to the Freeze Frame/Failure Records data that you observed.

Did the DTC fail this ignition?

Go to Step 3

Go to Diagnostic Aids

3 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 4 | --
4 |

1. Use the scan tool in order to clear the DTCs.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 5

Go to Step 2

5 | Use a scan tool, in order to observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | Go to Diagnostic Trouble Code (DTC) List | System OK