VOLVO
ECM-P233900 - Cylinder #4 Above Knock Threshold. General Failure Information. No sub type information
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS80 (2007–), V70 (2008–)
Show models by year and engine (2)
What does this fault code mean?
The engine control module (ECM) listens for combustion knock through a knock sensor on the engine block and retards the ignition when needed to stop the knock continuing. The code is set once knocking from cylinder 4 rises above a certain level, and
Possible causes
- The engine runs on a fuel/air mixture that is too lean
- Poor fuel quality, for example summer fuel in winter
- The engine is overheated
- The intake air temperature is too high
- The knock sensor is loosely fitted
- The knock sensor is damaged
What you can do
- 1The fuses should be intact; their locations are shown in the car's owner's manual
- 2Inspect the connector and cable to the knock sensor for loose contacts, corrosion and chafing
- 3Check that the knock sensor is firmly fitted to the engine block
- 4Check that the fuel is right for the season and that the engine has not overheated
- 5If you have a diagnostic tool, compare the intake air temperature in live data with the outside air temperature
- 6If the fault returns, have a workshop with diagnostic equipment check the knock sensor and the engine's fuel/air mixture
Symptoms you may notice1
- The engine performs poorly
General guidance for car owners. Diagnosis on the car can point to a different cause.