Circuit Description
This DTC will set if the knock system is otherwise functioning normally but is detecting excessive knock. This may be due to a noisy engine producing excessive mechanical vibrations from piston slap, valve closures, etc. Excessive knock could also be produced by very low octane fuel (85 octane or less).
Conditions for Setting the DTC
Test Conditions
| • | DTC(s) P0325 and P0327 not set. |
| • | Ignition voltage at least 10 volts. |
| • | Knock Learn is enabled. |
| • | Octane learn /lock-in not complete. |
Failure Condition
The 87 octane Decay Multiplier is 0.996 or more for 64 seconds.
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | No message will be displayed. |
Conditions for Clearing the DTC
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
2 | Start the engine. Does engine produce excessive mechanical noise? | -- | ||
3 | Locate and repair source of noise. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
4 | Inform owner that the use of premium fuel is required for optimum vehicle performance. Is premium fuel unavailable or does customer decide not to use premium fuel? | -- | ||
5 |
Serv. Spark will stay at set reading until changed with a scan tool or vehicle power to the PCM is disconnected. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
6 |
Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
