Cause
Faulty alternative fuel tank level sensor
The sensor reporting how much gaseous fuel is in the tank has failed, or its float arm has stuck.
Level has to be measured separately from pressure, because pressure cannot tell you how much is left. LPG sits in the tank as a liquid under its own vapour pressure, and that pressure is set by temperature rather than quantity — a nearly empty tank and a nearly full one read almost the same at the same temperature.
So the tank carries a float on an arm, read magnetically through the tank wall so that nothing electrical penetrates a pressure vessel. That arrangement is why these gauges are less accurate than a petrol sender, and why the commonest fault is mechanical rather than electrical: a float arm fouling on the tank wall or on debris, pinning the reading at one value while the circuit tests perfectly.
It matters more than a petrol gauge fault, because of the 80% rule. A gas tank is deliberately never filled beyond about four-fifths, leaving vapour space for the liquid to expand into as it warms. A tank whose level is misreported can be overfilled, and an overfilled tank warming in the sun has nowhere to expand.
The usual owner experience is a gauge nobody trusts and a car that runs out of gas without warning — recoverable, since it falls back to petrol, but worth fixing rather than working around.
Typically specialist work. Needs equipment or training most home workshops do not have.
Codes this can cause (13)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2A5F Alternative Fuel Tank B Level Sensor Circuit Likely for this code Moderate
- P2A60 Alternative Fuel Tank B Level Sensor Range/Performance Likely for this code Moderate
- P2A61 Alternative Fuel Tank B Level Sensor Circuit Low Likely for this code Moderate
- P2A62 Alternative Fuel Tank B Level Sensor Circuit High Likely for this code Moderate
- P2A63 Alternative Fuel Tank B Level Sensor Circuit Intermittent/Erratic Likely for this code Moderate
- P2A64 Alternative Fuel Tank C Level Sensor Circuit Likely for this code Moderate
- P2A65 Alternative Fuel Tank C Level Sensor Range/Performance Likely for this code Moderate
- P2A66 Alternative Fuel Tank C Level Sensor Circuit Low Likely for this code Moderate
- P2A67 Alternative Fuel Tank C Level Sensor Circuit High Likely for this code Moderate
- P2A68 Alternative Fuel Tank C Level Sensor Circuit Intermittent/Erratic Likely for this code Moderate
- P2BB0 Alternative Fuel Consumption Too Low Likely for this code Moderate
- P2BB1 Alternative Fuel Consumption Too High Likely for this code High
- P2BB2 Alternative Fuel Tank Empty Low
Information, not instruction
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