What does it mean?
U1131 is a Network (CAN bus, module communications) fault code. It indicates: Data Circuit Message .
Symptoms
- Fuel gauge reading wrong, stuck or dropping to empty while driving
- MIL (check engine lamp) on, often together with fuel level or fuel pressure codes
- Extended cranking, hesitation, stalling or a no-start condition
- Distance to empty and consumption displays showing nonsense values
- Fuel pump not priming or running continuously
- Faults that come and go with vibration or damp weather
Likely causes
- Break, chafe or short in the data circuit between the fuel system controller and the modules that use its information
- Corroded or wet connector at the fuel pump control module or at the tank sender connector
- Fuel pump control module without power or ground because of a blown fuse, a bad relay or a corroded ground point
- Fuel level sender circuit fault, so the fuel data broadcast on the network is implausible
- Internal fault in the fuel pump control module that stops it transmitting
- Damaged harness section where wiring crosses the rear suspension or frame
- Powertrain control module failure or interrupted programming
How to fix it
- Compare fuel level, fuel pressure and pump status in live data against the actual tank content and a mechanical pressure reading
- Inspect the fuel pump control module and tank connectors for corrosion, moisture and damaged pins
- Check the fuse, relay, supply voltage and ground for the fuel pump control module under load
- Test the serial data circuit between the fuel system controller and the receiving modules for opens and shorts
- Inspect the harness where it runs near the tank, rear suspension and frame for chafing
- Reproduce the fault with a wiggle test while the scan tool records fuel data
- Repair wiring and connectors first; replace the fuel pump control module or the sender only when they are proven faulty