P240E code meaning
Alternative Fuel High Pressure System Leak
Powertrain system Generic code P24xx codes Check engine light
What P240E means
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.
P240E at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P240E
- Check engine light, vehicle switches to gasoline or will not run on gas
- Gas gauge falls while parked
- Hissing noise or gas smell near the tank
Common causes of P240E
- Most 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
- Less likelyLeak at the high-pressure inlet of the regulator
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alternative fuel high pressure lineAlternative fuel shutoff valve
What each part of P240E means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 0E | The exact fault in that area. |
What to do next
- Note P240E and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P240E
What does P240E mean?
P240E means "Alternative Fuel High Pressure System Leak". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P240E?
Drive gently and only to a workshop. With P240E the car can go into limp mode (reduced power) to protect itself.
Will P240E fail an emissions test?
Yes, it can. P240E is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P240E to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P240E clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.