What does it mean?
P1658 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: FICM Detects Current Through Driver With Driver Off .
Symptoms
- MIL on, often with injector circuit codes for specific cylinders
- Hard starting, extended cranking, sometimes a no-start
- Rough idle and misfire on one or more cylinders
- Black smoke and a strong fuel smell from the exhaust
- Reduced power or limp mode, and the engine may stall under load
- Uneven combustion knock or a diesel-like clatter that changes with load
Likely causes
- Injector solenoid shorted internally so current keeps flowing after the driver turns off
- Injector harness chafed and shorted to ground, to the cylinder head or to another injector circuit
- Oil-soaked or wet injector connector under the valve cover, a classic failure point on these engines
- Failed output driver inside the FICM
- Corroded FICM connector or water entry into the module
- Poor FICM power feed or ground causing false current readings
- Harness damage where it passes through the valve cover pass-through connector
How to fix it
- Read all injector-related codes and FICM live data to identify which driver or cylinder is flagged
- Measure the resistance of each injector solenoid and compare the readings across all cylinders
- Remove the valve cover pass-through connector and inspect the under-cover harness for oil, chafing and melted insulation
- With the FICM unplugged, test each injector circuit for shorts to ground and for shorts between circuits
- Verify FICM supply voltage and ground quality with voltage-drop tests, and check the battery condition
- Repair or replace the damaged injector or harness section and clear the codes
- Replace and program the FICM only if a driver is still faulty with the injector harness disconnected