Code
P0071
LAND ROVER
P — Powertrain
Range / performance of ambient air temperature sensor
Views:
UK: 8
EN: 19
RU: 14
AI status
Completed
Completed
100%
Causes
- Faulty ambient air temperature (AAT) sensor (NTC thermistor)
- Open, short or high-resistance wiring between sensor and ECM
- Corroded or loose electrical connector or terminals
- Water ingress or physical damage to sensor
- Incorrect sensor installed or damaged harness/insulation
- Poor ground or power supply issue to the sensor circuit
Symptoms
- Malfunction Indicator Lamp (MIL) or check engine light
- Incorrect outside temperature display (dash) or no reading
- Automatic climate control may behave incorrectly
- Cold/hot start drivability may be affected slightly (fuel trim adjustments)
- Stored freeze-frame data showing abnormal AAT values
What to check
- Read and record freeze-frame and live AAT data with a scan tool
- Visual inspection of AAT sensor, connector and wiring for damage or contamination
- Check for water or dirt inside the sensor housing or connector
- Backprobe the signal and ground with a lab scope or multimeter while observing live data
- Measure sensor resistance at a known ambient temperature and compare to expected values
- Perform a wiggle test on harness while monitoring live AAT signal for intermittent faults
Signal parameters
- Typical sensor type: NTC thermistor (resistance decreases as temperature rises)
- Expected signal: 0–5 V (varies by vehicle); most circuits will show a mid-range voltage at ambient temps
- Common resistance reference: ~10 kΩ at ~25°C (varies by manufacturer; consult Land Rover spec if available)
- Usual operating range: sensor resistance in the order of 1 kΩ–100 kΩ across extreme temps
- Fault indications: open circuit → very high resistance/infinite, short to ground → ~0 V, short to battery → ~battery voltage
Diagnostic algorithm
- Connect a scan tool. Confirm P0071 and review freeze-frame data and live AAT reading versus actual outside temperature.
- Perform a visual inspection of the AAT sensor (usually located in front bumper, grille or HVAC intakes), harness and connector for damage, corrosion or water intrusion.
- With ignition on (engine off) backprobe the sensor connector. Measure signal voltage and ground reference while comparing to live data. Wiggle harness to check for intermittent changes.
- Disconnect sensor and measure sensor resistance across its terminals at ambient temperature. Compare reading to expected range (consult spec or compare to typical NTC behavior).
- If resistance or voltage is out of range, replace the AAT sensor and retest. If sensor checks good, perform continuity and resistance checks from sensor connector to ECM pin to find opens/shorts/high resistance.
- Repair any wiring/connector faults found (clean terminals, repair/replace harness, secure routing). Clear codes and test drive to verify code does not return.
- If wiring, connector and sensor are good and the fault persists, verify ECM input pin operation and consider ECM programming or replacement as a last resort (confirm with manufacturer guidance).
Likely causes
- Damaged/contaminated AAT sensor
- Connector corrosion or poor pin contact at sensor
- Open or shorted wiring (rodent damage, chafing, pinched harness)
- Faulty ECM input (least likely)
Fault status
Status
Ambient Air Temperature Sensor - Range/Performance. ECM has detected that the AAT sensor signal is outside the expected operational range or is inconsistent with sensor characteristics.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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