Faulty alternative fuel tank temperature sensor (open, shorted, or out-of-calibration element); Damaged or corroded wiring harness or connector at the sensor or PCM; High resistance or open circuit in the sensor signal or ground circuit; Failed or leaking alternative fuel tank pressure/temperature combination sensor (if integrated); PCM software calibration issue or internal driver fault (less common); Contamination or physical damage to the sensor from fuel quality or tank debris

DTC codes / P01xx · Fuel and air metering / P01AB

P01ABAlternative Fuel Tank Temperature Sensor Range/Performance

Q: What does code P01AB mean?

Alternative Fuel Tank Temperature Sensor Range/Performance. P01AB indicates that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the alternative fuel tank temperature sensor circuit. The computer compares the sensor's voltage or resistance against expected values for the current operating conditions and flags a fault when the reading falls outside a calibrated window or fails a rationality check.

P01AB indicates that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the alternative fuel tank temperature sensor circuit. The computer compares the sensor's voltage or resistance against expected values for the current operating conditions and flags a fault when the reading falls outside a calibrated window or fails a rationality check.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) on the dashboard
Often no symptoms besides the warning light, especially if the alternative fuel system continues to operate normally
Rough running or hesitation when switching between gasoline and alternative fuel
Poor fuel economy or unexpected changes in alternative fuel consumption
Hard starting or stalling when the vehicle is running on the alternative fuel
Incorrect fuel gauge or range display for the alternative fuel tank

Common causes, most likely first

Faulty alternative fuel tank temperature sensor (open, shorted, or out-of-calibration element)
Damaged or corroded wiring harness or connector at the sensor or PCM
High resistance or open circuit in the sensor signal or ground circuit
Failed or leaking alternative fuel tank pressure/temperature combination sensor (if integrated)
PCM software calibration issue or internal driver fault (less common)
Contamination or physical damage to the sensor from fuel quality or tank debris

How to diagnose and fix it

Connect a scan tool and record freeze-frame data and any stored or pending codes to confirm the fault conditions
Visually inspect the sensor, connector, and wiring for damage, corrosion, or loose pins
Measure the sensor's resistance or voltage at the connector and compare to the manufacturer's specification for the current temperature
Check the signal circuit for continuity and short-to-ground or short-to-power faults using a digital multimeter
Verify the ground circuit back to the PCM has low resistance and is secure
If the sensor is accessible, test it with a heat source while monitoring the scan tool data to confirm it responds smoothly and within range
Replace the sensor or repair the wiring as needed, clear codes, and verify the repair with a road test that includes alternative fuel operation

Why this code often misleads

A common trap is replacing the sensor when the real problem is a chafed wire near the tank that only shorts when the suspension moves, so always wiggle-test the harness while watching live data.
Some vehicles use a combined tank temperature and pressure sensor, and a pressure-side fault can set a temperature range code, so check both functions before condemning the part.
The PCM may set P01AB only after a cold-start rationality check, meaning the fault can be intermittent and not present during a warm bay inspection.
A weak or failing alternative fuel pump module can cause temperature fluctuations that mimic a sensor fault, so review fuel system live data alongside the temperature signal.
After repairs, some PCMs require a relearn or adaptation reset before the code will clear permanently, and skipping this step leads to a false comeback.

Can I keep driving with P01AB?

The vehicle is generally safe to drive with this code because it does not directly affect engine safety or emissions in most cases, but avoid extended driving if you notice rough running or fuel switching problems. Have the fault diagnosed soon to prevent potential alternative fuel system performance issues.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.