P2A9BAlternative Fuel Tank Select Valve C Control 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
- P2A9B is logged when the control circuit of tank select valve C reads below the expected level. Common electrical findings are a lead grounded against the frame, a pinched wire under a tank strap or a coil with internal shorts. What follows depends on how the output is wired: a ground-side driver may now keep valve C switched permanently, while a supply-side driver shuts down and lets the valve drop back. Either way the selection of the third vessel no longer follows the commands. Westport's two-vessel patent ties tank changes to empty-tank detection; with the valve out of control, that change may be skipped or forced. No manufacturer documents P2A9B or its voltage limits. Check the circuit with the valve unplugged first, then with the coil reconnected.
- What you may notice
- Malfunction lamp on
- Third tank used constantly or not at all
- Unexpected tank changes during the drive
- Likely causes
- LikelyLead of valve C grounded against the frame or pinched under a tank strap
- PossibleInternal short in the coil of valve C
- RareWater in the plug of valve C
- 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 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.