P2A8CAlternative Fuel Vaporizer B Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2A8C flags vaporizer B as underperforming: the gas leaving it is colder, or less completely vaporized, than the module expects for the current flow. With LNG the temperature gap is extreme, and Westport's patent CA2862664C describes the typical failure. At a cold start, at idle or under light load coolant crawls through the exchanger and can freeze inside it; flow then drops without stopping entirely, vaporizer capacity falls and the downstream gas temperature sinks, which can harm later components. Westport therefore runs fuel and coolant in parallel flow during start and idle and switches to counter flow afterwards. A stuck switching valve or ice can thus cause P2A8C. No manufacturer publishes the code or its limits.
- What you may notice
- Malfunction lamp on
- Reduced power or gas mode blocked, especially when cold
- Ice on the vaporizer or gas lines behind it
- Likely causes
- LikelyCoolant partly frozen inside vaporizer B after cold start or long idling
- PossibleValve that switches between parallel and counter flow stuck
- PossibleLow coolant level or too little antifreeze in the mixture
- RareDeposits reducing heat transfer in vaporizer B
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.