P0073

Code

MITSUBISHI P — Powertrain

Ambient air TEMP.sensor high

Brand: MITSUBISHI

Type: P — Powertrain

Views: UK: 10 EN: 22 RU: 66

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty ambient air temperature sensor
Open, short to voltage or poor connection in AAT sensor wiring or connector
Corroded or damaged sensor connector or terminals
Incorrect or aftermarket replacement sensor
Poor ground or reference voltage issue from ECM
Faulty ECM (rare)

Symptoms

Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
Incorrect ambient temperature reading on dash or HVAC controls
HVAC automatic climate control behaving incorrectly
Possible impact to engine control strategies that use ambient temp (cold start enrichment or fan control)

What to check

Scan vehicle for stored freeze-frame data and confirm P0073 is active/pending
Inspect AAT sensor location and connector for damage, corrosion, contamination, or water ingress
Monitor live AAT sensor data with a scan tool while changing ambient temperature (hand near sensor)
Check connector pins for bent, corroded or pushed-out terminals
Measure continuity/resistance/voltage at the sensor connector and at the ECM harness connector
Verify reference voltage and ground(s) at the sensor circuit per factory specification

Signal parameters

Typical AAT sensor circuit uses a thermistor with a pull-up; expected signal voltage usually between ~0.1–4.9 V depending on temperature (varies by vehicle)
Expected resistance varies with temperature; consult factory chart for exact Ω vs °C values
Activation criteria: voltage above the ECM’s upper threshold or open-circuit detection (refer to service manual)

Diagnostic algorithm

Retrieve freeze-frame and readiness data; confirm P0073 is current and note conditions when set.
Visually inspect the AAT sensor, mounting, and harness for damage, corrosion, insect/water ingress or loose connectors.
With ignition ON, monitor AAT sensor voltage/temperature via scan tool. Wiggle harness and connector to check for intermittent changes or fault occurrence.
Power and ground check: verify reference/pull-up voltage at the sensor connector and good ground continuity to chassis/ECM.
Measure sensor resistance vs temperature (or voltage) and compare to OEM specification. If open/high resistance or out of range, replace sensor.
Check continuity between sensor connector and ECM pins; repair any shorts to battery voltage or open circuits found.
If wiring and sensor check good, re-scan and, if fault persists, consider ECM/PCM fault and consult manufacturer procedures before replacement.

Likely causes

Damaged or corroded sensor connector or wiring
Open circuit or short to battery voltage in AAT sensor circuit
Failed ambient air temperature sensor element (thermistor)

Fault status

⚠️ Status

P0073 — Ambient Air Temperature Sensor High Input. ECM detected sensor signal above allowable upper threshold or open/high-voltage condition. Fault stored when abnormal condition present for required detection counts; MIL may be illuminated.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-1.5 hours

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P0073 — Ambient air TEMP.sensor high