P01AB code meaning
Alternative Fuel Tank Temperature Sensor Range/Performance
Powertrain system Generic code P01xx codes Check engine light
What P01AB means
These codes only apply to vehicles with a gaseous alternative fuel – compressed natural gas (CNG) or LPG – as bi-fuel models alongside gasoline or as dedicated gas engines; on bi-fuel vehicles a fault usually blocks gas operation and the vehicle runs on gasoline. The tank temperature sensor is an NTC thermistor: with CNG there is no float, so the gas level is calculated from tank pressure and tank temperature (GM: full at about 3600 psi at 21 °C, empty at about 400–500 psi). On GM's 2015 Impala Bi-Fuel the sensor is built into the tank and cannot be replaced separately. P01AB is the plausibility fault: the signal is valid but does not fit – for example compared with ambient temperature after standstill or with the pressure change while refuelling. No manufacturer document using exactly this code was found; the description rests on CARB, which treats such vehicles like gasoline engines for model years 2004–2018, and on the documented system design.
P01AB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P01AB
- Stored fault code (warning light depending on system)
- Gas level display wrong
- Gas operation blocked, switch to gasoline
Common causes of P01AB
- Most likelySensor drifting or stuck
- PossibleContact resistance in the connector
- Less likelyComparison sensor (tank pressure, ambient) wrong
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alternative fuel tank temperature sensorSensor wiring
What each part of P01AB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| AB | The exact fault in that area. |
What to do next
- Note P01AB 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 P01AB
What does P01AB mean?
P01AB means "Alternative Fuel Tank Temperature Sensor Range/Performance". These codes only apply to vehicles with a gaseous alternative fuel – compressed natural gas (CNG) or LPG – as bi-fuel models alongside gasoline or as dedicated gas engines; on bi-fuel vehicles a fault usually blocks gas operation and the vehicle runs on gasoline. It is a generic code, so it means the same on every make.
Is it safe to drive with P01AB?
Drive gently and only to a workshop. With P01AB the car can go into limp mode (reduced power) to protect itself.
Will P01AB fail an emissions test?
Yes, it can. P01AB 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 P01AB to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P01AB 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.