Powertrain, generic (extended)

P240E Alternative Fuel High Pressure System Leak

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Leaking high-pressure fitting or line between cylinder and regulator
Leaking tank valve or high-pressure cut-off solenoid
Leaking fill receptacle or its check valve
Leak at the high-pressure inlet of the regulator

Symptoms

  • 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

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–2,000
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

alternative fuel high pressure linealternative fuel shutoff valve

Related codes

P240DP0093P01A0

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, en.wikipedia.org.