P2A57Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2A57 sets when the outlet sensor on vaporizer B pulls its signal below the lowest valid voltage. On a thermistor that loses resistance with heat, as in the Ford CNG rail sensor, this would mean extreme heat, so the realistic causes are a signal lead grounded against the chassis and an internally shorted sensor. Long harness runs, common when the gas parts sit far from the controller, add chafing points. A falsely hot value is risky because the system could believe B is ready while it is cold. TransEco, for its comparable rail sensor fault, substitutes the intake air reading on dedicated systems and forces petrol on bi-fuel ones. No maker lists P2A57. Unplug the sensor: the reading must swing to cold, otherwise the harness is shorted.
- What you may notice
- Check engine light, depending on calibration
- Gas operation limited or switched off
- Vaporizer B shown far hotter than vaporizer A
- Likely causes
- LikelySignal lead of the B sensor grounded
- PossibleVaporizer B sensor shorted internally
- RareInsulation worn through on a long harness run
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.