Code
P0113
ISUZU
P — Powertrain
Intake Air Temperature Sensor Circuit High
Views:
UK: 24
EN: 63
RU: 95
AI status
Completed
Completed
100%
Causes
- Open or disconnected IAT sensor connector
- Corroded or bent pins at sensor or ECU connector
- Broken or damaged wiring (open or short to battery voltage)
- Failed IAT sensor (thermistor open or out of spec)
- Poor sensor ground or loss of reference/pull-up at ECU
- Faulty PCM (rare)
Symptoms
- Check Engine Light (MIL) illuminated
- Possible hard starting or extended crank time in some conditions
- Reduced fuel economy or drivability issues due to incorrect air-temp compensation
- Poor idle or hesitation under some conditions
- Failed emissions/inspection due to sensor fault
What to check
- Read freeze-frame/fault data and live IAT signal (voltage and computed temperature) with a scan tool
- Visually inspect IAT sensor and connector for corrosion, bent pins, contamination or water intrusion
- Wiggle harness while monitoring live IAT signal to check for intermittent faults
- Backprobe the IAT signal and measure voltage with key ON and engine running
- Measure sensor resistance at ambient temperature and compare to OEM spec (or check for open circuit)
- Check for continuity between the sensor signal/ground and the PCM connector; check for unintended shorts to battery voltage
Signal parameters
- Typical IAT sensor signal range: ~0.2–4.8 V (varies by vehicle and temperature).
- A 'high' input is commonly flagged when signal exceeds about 4.5–4.8 V or when the PCM reports an implausibly low temperature (often near -40 °C), indicating open circuit.
- IAT is usually an NTC thermistor: resistance decreases as temperature rises; open circuit = infinite/OL resistance.
- Use the vehicle's OEM specification for exact voltage/resistance/temperature values.
Diagnostic algorithm
- Verify the code and review freeze-frame/live data: note IAT voltage and calculated intake temperature.
- With ignition ON (engine OFF), visually inspect the IAT sensor connector and wiring for damage, corrosion, or poor mating. Repair as needed.
- Backprobe the IAT signal wire: measure voltage with ignition ON and engine running. If voltage is above the high threshold (>4.5 V typical) or is stuck at battery voltage, suspect open or short to battery.
- Unplug the sensor and measure sensor resistance across its terminals at ambient temperature. Compare to OEM spec. If resistance is infinite or far out of spec, replace the sensor.
- Check continuity from the sensor connector to the PCM pin. Look for open circuits or high resistance; repair wiring/harness faults.
- Check for short to battery voltage on the signal wire (probe between signal and battery +). If present, trace and repair short.
- If wiring and sensor are good, check that the ECM/PCM provides correct reference/pull-up and ground. If reference voltage is missing or incorrect, investigate PCM power/ground circuits.
- After repairs, erase codes and perform a test drive or recheck live data to confirm the code does not return.
- If all circuits and sensor are good but code persists, consider professional PCM diagnosis.
Likely causes
- Disconnected or corroded sensor connector
- Broken/open wiring between IAT sensor and PCM
- Failed IAT sensor (open circuit or out-of-spec resistance)
- Short to battery voltage on the signal circuit
- PCM input fault (least likely)
Fault status
Status
PCM detected an IAT sensor circuit voltage higher than expected (high input/open). Code P0113 stored. Possible causes include open or shorted wiring, bad connector, failed sensor, or rarely PCM fault.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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