Trouble Code Conditions
4-5-X, 5-4-3, 5-4-5, 5-5-X MISFIRE CYLINDER XTrouble Code Condition(s)
Diagnostic Trouble Codes EFI-45X, EFI-543:
- If the engine control module (ECM) registers more than 1% misfires in 1,000 engine revolutions (3,000 ignition sequences), the engine control module checks whether this misfiring comes from one specific cylinder or from different cylinders. If only one cylinder exceeds the limit, diagnostic trouble code (DTC) EFI-543 is stored first and then one of diagnostic trouble codes EFI-451, EFI-452, EFI-453, EFI-454, EFI-455 or EFI-456 depending on the cylinder. If more than one cylinder exceeds the limit diagnostic trouble code EFI-543 is stored with a diagnostic trouble code for the relevant cylinder.
Diagnostic Trouble Code EFI-55X, EFI-545:
- If the engine control module registers 6 - 50% misfiring, depending on engine speed and load, during 200 engine revolutions (600 ignition sequences), the engine control module checks if this misfiring comes from one specific cylinder or from different cylinders. If only one cylinder exceeds the limit, diagnostic trouble code EFI- 543 is stored first with one of diagnostic trouble codes EFI-451, EFI-452, EFI-453, EFI-454, EFI-455, or EFI-456 and EFI-545 and then one of diagnostic trouble codes EFI-551, EFI-552, EFI-553, EFI-554, EFI-555 or EFI-556 depending on the cylinder. If more than one cylinder exceeds the limit diagnostic trouble code EFI-545 is stored with a diagnostic trouble code for the relevant cylinder.
Substitute Value(s)
Diagnostic trouble codes EFI-45X, EFI-543:
- Fuel trim with rear heated oxygen sensor (HO2S) disabled.
- Long-term fuel trim disabled.
- Three-way catalytic converter (TWC) diagnostic disabled.
- Heated oxygen sensor diagnostic disabled.
Diagnostic Trouble Code EFI-55X, EFI-545:
- Fuel trim for both heated oxygen sensors disabled.
- Heated oxygen sensor aging diagnostic disabled.
- Long-term fuel trim disabled.
- Three-way catalytic converter diagnostic disabled.
- EVAP diagnostic is disabled.
- Short-circuit in heated oxygen sensor signal cable and ground lead blocked.
Possible Source(s)
- Defective spark plugs, ignition cables, ignition coils or flywheel/pulse wheel.
- Blocked/leaking injector.
- Uneven compression.
- Leakage between cooling system and cylinder.
- Moisture, flashover in ignition system HT side.
- Intermittent open-circuit , intermittent short-circuit to ground, intermittent short-circuit to voltage supply, contact resistance or loose connection in ignition system low-tension side, in injector circuit or fuel pump (FP) circuit.
- Engine oil level too high air leakage fuel pressure and residual pressure.
Fault Causes Not Included In The Fault-tracing Process, But Which May Still Post A Diagnostic Trouble Code:
- Fuel stoppage.
- Water in spark plug wells .
- Contaminated fuel or incorrect fuel.
- Repeated cold starting where the engine coolant temperature (ECT) is not allowed to reach operating temperature between starts.
Fault Symptom(s)
- Engine does not start, or is difficult to start.
- Engine runs unevenly at idling speed, or jerkily while driving.
- Poor performance.
- High emissions.
- Glowing pieces of three-way catalytic converter failing out of the exhaust pipe.