P1231 MERCURY Possible Causes
- Faulty high-speed fuel pump
- High-speed fuel pump wiring harness open or shorted
- Poor electrical connection in the high-speed fuel pump circuit
How to Fix Code P1231 MERCURY?
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 service warning light soon)
P1231 MERCURY Meaning
The Engine Control Module (ECM) has powered the high-speed fuel pump and detected no current flow in the circuit.