P240EAlternative Fuel High 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
- P240E concerns the high-pressure side of a gaseous alternative-fuel system, from the storage cylinder through the tank valve and high-pressure line and filter up to the regulator. Pressures there are far higher than in the rail: CNG is stored at about 200-250 bar, and GM's PI1330 rates the 2015 Impala bi-fuel tank at 3,600 psi, with a high-pressure cut-off solenoid at the tank and a coalescing filter that is drained every 15,000 miles. LPG systems run at up to about 300 psi according to GM. No manufacturer publicly documents how P240E is detected; a loss of tank pressure that is not explained by consumption is the likely trigger. CARB treats CNG and LPG engines as alternate-fueled. P240D covers the regulated low-pressure side. Treat any warning as urgent, since gas escapes quickly at these pressures.
- What you may notice
- Check engine light, vehicle switches to petrol or will not run on gas
- Gas gauge falls while parked
- Hissing noise or gas smell near the tank
- Likely causes
- LikelyLeaking high-pressure fitting or line between cylinder and regulator
- PossibleLeaking tank valve or high-pressure cut-off solenoid
- PossibleLeaking fill receptacle or its check valve
- RareLeak at the high-pressure inlet of the regulator
- 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 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.