P1189 Possible Causes
- Faulty fuel filter
- Faulty injector
- Faulty electric fuel pump
- Faulty fuel pressure regulator (FPR)
- Faulty rail pressure sensor (RPS)
- Engine control module (ECM)
How to Fix Code P1189?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Engine light on (or engine warning light soon in service)
P1189 Meaning
Fuel pressure monitoring is used to detect fuel problems and leaks in the high-pressure system.
The engine control module (ECM) determines the rail pressure value based on engine operating conditions and controls the fuel pressure regulator to ensure the rail pressure reaches the required value.
The fuel pressure in the fuel line, including pumps and injector, is continuously monitored during engine operation.
If the rail pressure is excessive, the fuel pressure regulator opens and some fuel is returned from the rail to the fuel tank via a collector line. If the rail pressure is too low, the fuel pressure regulator closes.
The fuel pressure regulator closes. the fuel pressure regulator is installed at the rear end of the high-pressure accumulator.
In case of insufficient fuel supply in the fuel line, engine symptoms will occur such as stalling and inability to start.
If the fuel pressure monitoring in the engine’s fuel pressure line generates a threshold value, the ECM judges it as a fault and the P1189 code is set.