P240D code meaning
Alternative Fuel Low Pressure System Leak
Powertrain system Generic code P24xx codes Check engine light
What P240D means
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.
P240D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P240D
- Check engine light, gas mode may be disabled
- Gas smell in the engine bay
- Higher gas consumption
Common causes of P240D
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alternative fuel low pressure lineAlternative fuel shutoff valve
What each part of P240D 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). |
| 0D | The exact fault in that area. |
What to do next
- Note P240D 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 P240D
What does P240D mean?
P240D means "Alternative Fuel Low Pressure System Leak". P240D applies only to vehicles running on a gaseous alternative fuel such as CNG or LPG, which CARB counts as alternate-fueled. It is a generic code, so it means the same on every make.
Is it safe to drive with P240D?
Drive gently and only to a workshop. With P240D the car can go into limp mode (reduced power) to protect itself.
Will P240D fail an emissions test?
Yes, it can. P240D 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 P240D to fix?
Difficulty: hard. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P240D 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.