Powertrain, generic (extended)

P2BB1 Alternative Fuel Consumption Too High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2BB1 is set when the alternative fuel store, typically a CNG cylinder, loses more gas than the injected quantity can account for. The main suspicion is a leak between tank and injectors, which is why this check doubles as a safety monitor. FCA's patent US9284895 describes it for natural gas vehicles: tank pressure is sampled at two moments, the gas mass delivered per cylinder charge is integrated over the same period, and a leak is flagged when actual use exceeds the expected figure by more than a tolerance, about 3 % or 2 mg per second and cycle in its example. No carmaker publishes P2BB1 itself. A sensor that exaggerates the pressure drop or an injector stuck open can produce the same result. Smell gas: park outdoors and have it checked. Too little use is P2BB0.

Likely causes

Gas leak at fittings, lines, regulator or tank valve
Gas injector leaking or sticking open
Tank pressure or temperature sensor exaggerating the pressure drop

Symptoms

  • Gas range much shorter than usual
  • Gas smell around the vehicle
  • MIL on, gas mode may be locked out

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,200
Time1–4 h

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

Parts involved

alt fuel injectorsalt fuel railalt fuel pressure regulator

Related codes

P2BB0P2BB2P01A9P019EP01AA

References: law.cornell.edu, patents.google.com, static.nhtsa.gov.