What it means
Voltage on the pressure sensor signal line of alternative fuel tank C is above the expected window. Wire shorted to B+ or sensor open.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The AFCM monitors the signal voltage from the pressure sensor on alternative fuel tank C. This code sets when the signal is above the expected range, which can result from a signal wire shorted to battery voltage, an open sensor, or a poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open pressure sensor
- Connector pins corroded - high contact resistance
Symptoms
- Alternative-fuel system warning light, if equipped
- Fuel level or remaining range may be inaccurate
- Alternative-fuel operation may be limited
How to diagnose it
- Review freeze-frame and live data to see whether tank C pressure is fixed high or becomes implausible when the fault occurs.
- Inspect the tank C sensor connector and harness for corrosion, loose pins, and contact with power wires.
- Use the manufacturer's wiring information to verify sensor power and ground and identify the signal wire.
- Test the signal circuit for a short to battery voltage and check continuity from the tank C sensor to the AFCM.
- If the circuit is intact, test the tank C pressure sensor for an open condition using the manufacturer's procedure.
Common fixes
- Reconnect or clean the tank C pressure-sensor connector and repair damaged pins.
- Repair a signal wire shorted to battery voltage or an open in the circuit.
- Replace the tank C pressure sensor if it is open or fails the specified test.
Can I keep driving?
Tank C fuel level or remaining range may be wrong, and alternative-fuel use may be restricted. Avoid relying on the range display; if the vehicle runs poorly or the fuel-system warning escalates, stop using alternative fuel and follow the vehicle's instructions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.