P2A42Alternative Fuel Tank B Pressure Sensor Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Unlike its electrical siblings, P2A42 deals with a tank B pressure reading that is electrically valid but makes no sense. Examples: the value does not fall while gas is drawn from tank B, it stays frozen after refuelling, or it differs clearly from the pressure of the other cylinders after a long stop, when all tanks connected to one fill line should settle at about the same level. New Flyer's bulletin SMB-169 for CNG buses gives a sense of the scale: after filling, the high-pressure gauge is expected to show between 200 and 3,600 psi. A tank valve stuck closed (P2A23) or a closed hand valve also starves the reading of change. No manufacturer publishes P2A42 or its limits; CARB requires a rationality check for such inputs. Diagnosis compares the sensor with a mechanical gauge.
- What you may notice
- Check engine light
- Gas gauge implausible after refuelling or driving
- Reduced range on gas
- Likely causes
- LikelyTank B pressure sensor drifting or stuck
- PossibleTank B solenoid stuck closed or manual valve shut
- PossibleContact resistance in the sensor connector shifting the signal
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.