01 What is a Hybrid Car and How Does it Work? A Fun and Easy E… • 02 The Importance of Timing Belt Replacement: Preventing Engin… • 03 Avoid These Brake Pads If You Drive in Rainy or Coastal Reg… • 04 Top 7 Reasons Your Car Loses Power: Troubleshooting Common … • 05 How to Start an Automotive Business With Almost No Capital • 06 This Is How Brain-To-Vehicle Interface Technology Works • 07 P0300: Random or Multiple Cylinder Misfire Detected – Cause… • 08 C0070 and C0075: Right Front ABS Solenoid #1 and #2 Circuit… • 09 Is There Any Significant Difference Vetween 1.6L and 2.0L E… • 10 This Is Why Your Car Won’t Start Even With A New Battery •

DTC codes / P01xx · Fuel and air metering / P01AE

P01AEAlternative Fuel Tank Temperature Sensor Circuit Intermittent/Erratic

P01AE indicates that the powertrain control module (PCM) has detected an intermittent or erratic signal from the alternative fuel tank temperature sensor circuit. The PCM expects a stable voltage or resistance value that correlates with the temperature of the alternative fuel tank, but the signal is jumping or dropping out unpredictably.

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 fault is intermittent.
  • Erratic or inaccurate fuel gauge readings for the alternative fuel tank.
  • Poor engine performance or drivability issues when running on alternative fuel.
  • Difficulty starting or stalling when the vehicle is operating in alternative fuel mode.
  • Possible reduced fuel economy or power if the PCM defaults to a limp-home strategy.

Common causes, most likely first

  1. Faulty alternative fuel tank temperature sensor.
  2. Damaged or corroded wiring harness or connector at the sensor.
  3. Loose or poor electrical connection at the PCM or sensor.
  4. Open or short circuit in the sensor signal or ground circuit.
  5. Water intrusion or contamination in the connector or sensor.
  6. Failed PCM (rare, but possible after other causes are ruled out).

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related codes in the alternative fuel system.
  2. Inspect the sensor and its connector for physical damage, corrosion, or loose pins.
  3. Measure the sensor resistance with a multimeter and compare to the manufacturer's specification for the current temperature.
  4. Check the wiring harness for continuity and shorts between the sensor and the PCM, wiggle-testing the harness while monitoring the signal.
  5. If the sensor is faulty, replace it and clear the codes to see if the fault returns.
  6. If wiring is damaged, repair or replace the affected section and ensure proper routing away from heat and moving parts.
  7. After repairs, perform a road test and monitor the sensor signal with a scan tool to confirm the code does not reset.

Intermittent faults often hide in the harness

  • A common oversight is replacing the sensor without checking the harness, but intermittent codes are frequently caused by chafed wires or loose connectors that only act up under vibration or temperature changes.
  • The alternative fuel tank temperature sensor may share a ground or reference voltage with other sensors, so a fault in a related circuit can cause this code to set even if the sensor itself is good.
  • Some vehicles use a fuel temperature sensor that is integrated into a fuel composition sensor or module, making the entire assembly the replacement part rather than a standalone sensor.
  • The PCM may set this code only after multiple drive cycles with an erratic signal, so the fault may not be present during a quick inspection; a data logger or oscilloscope can capture intermittent glitches.
  • Do not overlook the possibility of a poor connection at the PCM connector, especially if the vehicle has been exposed to moisture or has had recent electrical work.

Can I keep driving with P01AE?

If the vehicle is running normally, you can drive it to a repair shop, but avoid heavy loads or long trips until the fault is diagnosed. If the engine runs poorly or stalls, stop driving and have the vehicle towed to prevent safety risks.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage