P0091Powertrain
Powertrain · SAE
Fuel Metering Valve 1 — Low Input
Meaning
The engine control module has detected that the control signal or voltage in the fuel metering valve (IMV/FMV) circuit of fuel system 1 is consistently below the minimum expected threshold. The circuit is shorted to ground, open, or the valve has abnormal internal resistance.
Common causes
- Metering valve signal or supply wire shorted to ground
- Faulty metering valve with abnormal internal resistance or open circuit
- Corroded connector or pushed-back pins creating high resistance
- ECM output driver for valve control shorted to ground
- Open in the wiring between the ECM and the metering valve
- Blown fuse in the valve supply circuit
Symptoms
- Check-engine light (MIL) illuminated
- Low or absent rail pressure
- Hard start or no-start
- Rough idle and power loss
- White smoke or unburned fuel cloud from the exhaust
Severity
Very high: a metering valve shorted to ground delivers no or insufficient fuel to the HP pump; the engine may not start or may stall.
What to do
- Measure resistance and voltage in the metering valve circuit with ignition ON
- Check for short to ground on the signal and control wires
- Verify wiring continuity between the ECM and the valve
- Inspect the connector for oxidation, pushed-back pins, or moisture
- Replace the metering valve if wiring is serviceable and the short is internal