What does it mean?
P1094 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Fuel Rail Pressure Solenoid Circuit Malfunction .
Symptoms
- Engine hard to start or will not start at all
- Severe power loss with the vehicle dropping into limp mode
- Rough, uneven running and stalling at idle
- Check engine light on, usually as a hard fault
- Rail pressure in live data far away from the requested value
- Noisy running or smoke from the exhaust as fuelling goes out of control
Likely causes
- Corroded or loose connector at the pressure control solenoid on the high-pressure pump
- Open circuit or short in the solenoid control wiring, often where the loom runs close to the engine
- Solenoid coil that has gone open or shorted internally
- Blown fuse or a failed relay in the solenoid supply feed
- Chafed harness earthing the control wire against the pump body or a bracket
- Fuel or moisture ingress into the connector
- Failed ECM (engine control module) driver stage, considered last
How to fix it
- Compare desired and actual rail pressure in live data while cranking and at idle to confirm the pressure control is not responding
- Check the fuse and the supply voltage at the solenoid connector with the ignition on
- Measure the solenoid coil resistance and compare it with the specification; an open or very low reading condemns the valve
- Test the control wire for continuity to the module and for an unintended short to ground
- Inspect the connector and the surrounding harness for fuel contamination, corrosion and chafe damage
- Repair the wiring fault or renew the pressure control solenoid, observing the cleanliness rules for high-pressure fuel components
- After the repair, clear the codes and verify rail pressure follows the requested value across idle and load