Code
P0073
LAND ROVER
P — Powertrain
ambient air temperature sensor - High input of the control circuit of the intake valve
Views:
UK: 11
EN: 21
RU: 49
AI status
Completed
Completed
100%
Causes
- Open or high-resistance wiring in the AAT sensor circuit
- Short to battery voltage in the AAT harness or connector
- Corroded or loose sensor connector pins
- Faulty ambient air temperature sensor (thermistor)
- Poor or missing ground at sensor/ECU
- Intermittent wiring damage (chafing, pinched cable)
Symptoms
- Malfunction Indicator Lamp (MIL) or check engine light illuminated
- Incorrect exterior temperature readout on dash or climate control
- Climate control behavior may be erratic (incorrect auto climate responses)
- Engine may run slightly rich/lean during cold start or incorrect idle behavior in some vehicles
- Stored freeze frame data showing high sensor voltage
What to check
- Retrieve live data with a scan tool: monitor AAT sensor voltage and reported temperature
- Compare reported ambient temperature to actual ambient temperature
- Check for any related stored codes (IAT/AAT/IAT high/low)
- Visually inspect AAT sensor location and connector for corrosion, damage or water intrusion
- Backprobe connector and measure sensor circuit voltage with ignition ON (do not start)
- Measure resistance of sensor at ambient temperature and compare to specification (thermistor should show reasonable resistance for real ambient temp)
Signal parameters
- Expected signal type: thermistor (temperature-dependent resistance) producing a voltage signal to ECU via pull-up (NTC: resistance decreases as temperature increases)
- Typical idle/ambient voltage range: ~0.2–4.8 V depending on design (High input means voltage near supply or above expected threshold)
- High input indicates voltage above the upper threshold configured by the ECU (often close to battery or reference supply)
- Resistance should correlate to ambient temperature (consult vehicle-specific chart for exact ohms/°C)
Diagnostic algorithm
- Connect a scan tool and confirm P0073 and any related codes; record freeze frame data and live AAT voltage/temperature
- Visually inspect the AAT sensor and harness for obvious damage, corrosion, or water ingress; repair as needed
- With ignition ON (engine off) backprobe the sensor connector: measure reference voltage, signal voltage, and ground presence. Check for short to battery if signal is high
- Measure sensor resistance at ambient temperature and compare to specification. If resistance is open or out-of-range, replace the sensor
- If the sensor reads correctly, check continuity between the sensor signal pin and the ECU input pin; check for shorts to battery voltage on the harness
- Repair any wiring connector faults, replace the sensor if confirmed faulty, then clear codes and road test to verify code does not return
- If wiring and sensor verify good and fault persists, consider ECU input driver fault and refer to manufacturer procedures for module testing or replacement
Likely causes
- Damaged connector or corrosion at the AAT sensor
- Broken or disconnected wiring between sensor and ECU
- Sensor internal failure (open thermistor or out-of-spec resistance)
- Short to battery voltage due to exposed conductor contacting power feed
Fault status
Status
Ambient Air Temperature sensor circuit - High input detected. Signal voltage above expected range (possible open/high resistance, short to battery voltage, sensor or connector fault). MIL set.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email