Electrical and sensors

P0071 — Ambient Air Temperature Sensor Circuit Range/Performance

Severity: low Safe to drive

What P0071 means

The control module reads the outside air temperature sensor and compares it with other data, such as intake air temperature, coolant temperature after a long cold soak and vehicle speed. If the reading is unrealistic or does not change as expected, it sets P0071. This data helps with some engine adjustments, climate control and the outside temperature display.

Symptoms

  • Check engine light on
  • Wrong or stuck outside temperature on the dash
  • Automatic climate control behaving oddly
  • Occasionally slightly rough idle after a cold start
  • Minor drop in fuel economy

Possible causes

  1. Failed ambient air temperature sensor
  2. Open circuit, short or corroded contacts in the wiring or connector
  3. High resistance in the circuit from corrosion or damaged insulation
  4. Sensor mounted near a heat source or damaged by impact (for example behind the bumper)
  5. Fault in the control module input circuit or in another module sharing the signal over the network
  6. Software glitch (rare)

How to diagnose

  1. Read all codes and freeze frame data, then clear the code and see if it returns.
  2. In live data, compare ambient temperature with intake air and coolant temperature on a cold engine; they should be close.
  3. Inspect the sensor, connector and harness for damage, moisture, corrosion and impact marks.
  4. Measure the sensor resistance and compare it to the manufacturer's chart for the current temperature.
  5. Check for a reference voltage (typically about 5 V) and a good ground at the sensor connector.
  6. Test the wiring between the sensor and the module for opens and shorts to ground or power.
  7. If sensor and wiring are good, check the module input circuit and look for software updates.

Common fixes

  • Replace the ambient air temperature sensor
  • Repair the wiring or replace the connector
  • Fix the cause of heat exposure or damage at the sensor location
  • Update software or replace the control module (rare)

Questions and answers

What does P0071 mean?

The ambient air temperature sensor signal is out of range or does not match expected values. The sensor or its wiring is most often at fault.

Can I drive with code P0071?

Yes, it is usually safe and does not hurt the engine. Fix it so the climate control and temperature display work correctly.

How do I test the ambient air temperature sensor?

Compare its reading on a scan tool with intake air temperature on a cold engine. Then measure its resistance and check for voltage and ground at the connector.

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.