DTC EFI-621

Trouble Code Condition(s)
- Diagnostic trouble code (DTC) EFI-621 (Fuel tank pressure sensor, signal) is stored if the engine control module (ECM) receives a signal from the tank pressure sensor corresponding to a pressure above 2.95 kPa (0.4 psi) (signal high) or below -2.95 kPa (0.4 psi) (signal low).
- Diagnostic trouble code EFI-621 is stored it the signal is unstable (signal sporadic) for 25 seconds.

Substitute Value(s)
- Leakage diagnostic is disabled.

Possible Source(s)
Signal too high:
- Short-circuit to supply voltage in signal cable.
- Open-circuit in signal cable or ground lead.
- Contact resistance in terminals.
- Defective fuel tank pressure sensor.

Signal too low:
- Short-circuit to ground in signal cable.
- Open-circuit in power cable.
- Short-circuit to ground in air conditioning (A/C) pressure sensor.
- Short-circuit to ground in accelerometer power cable.
- Short-circuit to ground in power cable.
- Contact resistance in terminals.
- Defective fuel tank pressure sensor.
- Defective air conditioning pressure sensor.
- Defective atmospheric pressure sensor.
- Defective accelerometer.

Signal sporadic:
- Loose connections.
- Contact resistance in terminals.
- Defective air conditioning pressure sensor.
- Defective accelerometer.
- Defective fuel tank pressure sensor.

Fault symptom(s)
- None.