P01AE
Alternative Fuel Tank Temperature Sensor Circuit Intermittent/Erratic.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 1
- AreaFuel and air metering
- AE
- FaultThe specific fault in that area
What it means
P01AE means the engine control unit has seen an intermittent or erratic signal from the temperature sensor on the alternative fuel tank, such as a gas (LPG or CNG) or other secondary fuel tank. The signal jumped, dropped out or changed faster than a real tank temperature could. The sensor circuit is monitored, so the fault is set when readings are implausible or keep switching between valid and invalid.
Symptoms
- Engine warning light on
- Alternative fuel mode unavailable or the car stays on petrol or diesel
- Fuel switchover delayed or happening at odd times
- Alternative fuel gauge or level reading flickering or incorrect
- Poor running or reduced power on the alternative fuel
- Fault appearing and disappearing, especially over bumps or in changing temperatures
Possible causes
- Loose, corroded or damaged connector at the tank temperature sensorlikely
- Chafed, stretched or broken wiring between the sensor and the control unit causing intermittent open or short circuitslikely
- Faulty tank temperature sensor, or a combined pressure and temperature sensor, with an internal intermittent faultpossible
- Water ingress or contamination in the sensor connector or harnesspossible
- Poor earth or unstable reference voltage supply to the sensorpossible
- Fault in the alternative fuel control unit or engine control unit, or outdated software where the manufacturer has documented it as a causerare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting temperature, engine state and when the fault set, and look for other alternative fuel or sensor supply codes.
- Check live data for the tank temperature reading and see whether it jumps, drops out or disagrees with ambient temperature on a cold car.
- Inspect the sensor connector and harness for damage, corrosion, moisture, bent pins and poor terminal tension, and check the routing for chafing or heat damage.
- Wiggle test the harness and connector with the engine running while watching the live reading for spikes or dropouts.
- Check the sensor circuit's reference voltage, signal and earth against the manufacturer's wiring diagram, and test for voltage drop on the earth.
- Measure the sensor resistance at a known temperature and compare it with the specification for that model, as the sensor type varies by vehicle and fuel system.
- Check for any software updates or technical bulletins for the model and fuel system, and only consider control unit faults after the wiring and sensor are proven good.
How to fix
- Clean and secure the connector, or replace it and any damaged terminals.
- Repair or replace damaged wiring, and secure the harness away from heat and abrasion.
- Replace the tank temperature sensor, or the combined sensor assembly, if it tests faulty. Gas system work should be done by someone qualified for that fuel system.
- Dry out and seal the connector and replace any water-damaged parts.
- Repair the earth or supply fault, then clear the code and road test to confirm it does not return.
- Update the control unit software only if the manufacturer lists it as a fix for this fault, or replace the control unit if proven faulty.
Can I keep driving?
The car can usually keep being driven on its main fuel, but the alternative fuel system may be limited or unavailable. Have it checked soon, and stop and seek help if you smell gas or fuel.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.