P240DAlternative Fuel Low Pressure System Leak
- 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
- P240D applies only to vehicles running on a gaseous alternative fuel such as CNG or LPG, which CARB counts as alternate-fueled. It indicates a leak in the low-pressure part of the gas system, downstream of the pressure regulator. GM's bulletin PI1330 for the 2015 Impala bi-fuel shows this layout: the regulator reduces tank pressure to 68-130 psi, a low-pressure cut-off solenoid feeds a filter and oil separator and then the gas rail, and a relief valve caps that side at 290 psi if it is opened. How P240D is detected is not published by any manufacturer; a plausible approach is watching how pressure behaves with the shut-off valves closed. P240E is the matching code for the high-pressure side. A gas leak is a safety issue: stop using the gas system and have it inspected.
- What you may notice
- Check engine light, gas mode may be disabled
- Gas smell in the engine bay
- Higher gas consumption
- Likely causes
- LikelyLeaking fitting or hose on the regulated low-pressure side
- PossibleLeaking seal at the low-pressure filter or oil separator housing
- PossibleGas rail or gas injector seal leaking
- 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 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.