Engine

P011E — ECT Sensor and Ambient Air Temperature Correlation Fault

Severity: medium Safe to drive

What P011E means

After the engine has sat off for several hours, coolant temperature should be close to the outside air temperature. The PCM compares the coolant and ambient sensor readings at startup. If they differ more than they should, it sets P011E. The cause can be either sensor or the wiring between them and the PCM.

Symptoms

  • Check Engine light on
  • Erratic or implausible coolant temperature readings
  • Unusual engine warm-up behavior
  • Rough idle or reduced fuel economy
  • Wrong outside temperature shown on the dash
  • Harder starting, especially when cold

Possible causes

  1. Failed engine coolant temperature sensor
  2. Failed ambient air temperature sensor
  3. Open, shorted or high-resistance wiring or connectors at either sensor
  4. Corrosion or moisture in a sensor connector
  5. Rarely, a PCM software or hardware fault

How to diagnose

  1. Scan for all codes and review freeze frame data, looking for other temperature sensor codes
  2. Let the car cool off completely (several hours), then compare coolant, ambient and intake air temperature readings on a scan tool
  3. Compare the readings with a real thermometer
  4. Inspect both sensor connectors and harnesses for corrosion, damage or moisture
  5. Measure sensor resistance and compare to the spec for that vehicle
  6. Check reference voltage and ground at the sensor connector with a multimeter
  7. Wiggle the harness while watching live data to catch intermittent dropouts

Common fixes

  • Replace the engine coolant temperature sensor
  • Replace the ambient air temperature sensor
  • Repair the wiring or replace a damaged connector, and clean the terminals
  • Update or replace the PCM only if everything else tests good

Questions and answers

What does P011E mean?

The PCM found that the coolant temperature sensor and the ambient air temperature sensor don't agree when they should. It's most often a bad sensor or a wiring problem.

Can I drive with P011E?

Usually yes, but get it checked soon. Bad temperature data can hurt starting, idle quality and fuel economy.

How do I tell which sensor is bad?

Let the engine cool fully and compare both readings on a scan tool with a real thermometer. The one that is far off is the suspect; then test its resistance and wiring.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.