P019F Alternative Fuel Tank A Pressure Sensor Performance

These codes only apply to vehicles that run on a gaseous alternative fuel – compressed natural gas (CNG) or LPG – either as bi-fuel models alongside petrol (for example GM's 2015–2016 Impala Bi-Fuel or 2013–2016 Silverado/Sierra 2500HD) or as dedicated gas engines. CNG is stored at up to about 250 bar (3600 psi); a regulator reduces it to a few bar for the gas rail and injectors. The tank pressure sensor A sits at or in the regulator; together with the tank temperature it gives the gas level, and it decides whether gas operation is possible. P019F is the plausibility fault: the signal is electrically valid but does not fit – for example it is stuck or offset, or does not match tank temperature and gas consumption. A tank shut-off valve that does not open, or a closed manual tank valve, also leaves the sensor at the regulator without tank pressure. Work on the high-pressure side should only be done by trained technicians after depressurising the system. Typical reaction: gas operation is blocked and a bi-fuel vehicle switches to petrol. No manufacturer document naming exactly this code was found; GM's bulletins only state that faults are reported like on petrol models. The description rests on CARB, which treats such vehicles like petrol engines for model years 2004–2018, and on the documented system design.

Likely causes

Symptoms

• Check engine light on
• Gas level gauge wrong, jumping or showing empty
• Gas operation blocked or automatic switch to petrol
• Dedicated gas engines: limp mode or starting problems possible

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.