P0110

Intake Air Temperature Circuit Malfunction Bank 1

P0110 is a generic OBD-II powertrain diagnostic trouble code: Intake Air Temperature Circuit Malfunction Bank 1. It is logged by the engine control unit when the air/maf monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0110
Group
Powertrain
System
Air/MAF
Severity
Warning (MIL on)
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What P0110 means

P0110 is stored when the PCM detects that the Intake Air Temperature sensor 1 (IAT1) circuit signal has moved outside the expected voltage window for a duration exceeding the manufacturer's threshold. Unlike the intermittent codes P0112/P0113, P0110 represents a general circuit malfunction — the signal may be stuck high or low, or oscillating erratically — indicating either a failed sensor, an open or shorted wiring circuit, or a contaminated sensing element.

On modern engines the IAT1 sensor is frequently integrated into the mass airflow (MAF) sensor housing, making a wiring or connector fault at the MAF assembly the most common cause of this code. The sensor uses a negative-temperature-coefficient (NTC) thermistor; its resistance decreases as temperature rises, producing a voltage signal the PCM uses to calculate incoming air density and adjust fuel delivery, ignition timing, and boost pressure targets accordingly. An incorrect IAT reading causes the PCM to miscalculate air-fuel ratio, particularly impacting cold-start enrichment and detonation protection under high load.

Begin diagnosis with a visual inspection of the IAT/MAF connector for corrosion, bent pins, or moisture ingress, then verify the 5 V reference and signal-ground circuits with a multimeter. Measure sensor resistance across its terminals and compare to the manufacturer's temperature-resistance chart (typically ~2.5 kOhm at 20 degrees C). If the circuit checks out and resistance is within spec, suspect contamination of the sensor tip with oil mist from a crankcase ventilation leak, which can alter thermal response and produce an incorrect voltage.

Common causes

Most-frequently reported root causes when P0110 is logged.

  • 1
    Failed IAT1 sensor with an open or internally shorted thermistor producing a continuously out-of-range voltage.
  • 2
    Corroded, damaged, or poorly seated connector at the IAT or MAF/IAT combined sensor assembly.
  • 3
    Open circuit in the signal wire or ground wire between sensor and PCM (chafed, broken, or pinched).
  • 4
    Short to ground or short to battery voltage on the signal wire pulling the reading to 0 V or 5 V.
  • 5
    Oil mist contamination of the sensor tip from a crankcase breather leak altering thermal resistance.
  • 6
    Unmetered air entering downstream of the sensor (e.g., cracked air intake ducting) causing implausible temperature readings.
  • 7
    PCM internal input circuit fault misreading a valid sensor signal.

Symptoms drivers notice

Check engine light on with P0110 stored (may accompany MAF or fuel trim codes if sensor is combined).
Poor cold-start performance — excessive cranking, rough idle, or rich exhaust smoke on startup.
Reduced fuel economy caused by incorrect air-density calculations skewing the fuel map.
Hesitation or stumble during acceleration, especially under load.
Increased exhaust emissions due to incorrect air-fuel ratio management.
Possible knock or detonation if IAT is reported falsely low, causing the PCM to advance ignition timing.

How to diagnose P0110

A typical diagnostic flow when this code is present.

  1. 1
    Visually inspect the IAT/MAF connector for corrosion, bent pins, moisture, or cracked housing; clean with electrical contact cleaner if contaminated.
  2. 2
    With the key on and engine off, verify approximately 5 V reference voltage and a solid ground at the sensor connector using a multimeter.
  3. 3
    Measure resistance across the IAT sensor terminals and compare to the manufacturer's temperature-resistance specification (commonly ~2.5 kOhm at 20 degrees C, ~300 Ohm at 80 degrees C); replace sensor if out of spec.
  4. 4
    Inspect the wiring harness from the sensor to the PCM for chafe, pinch points, and heat damage; test signal wire continuity and check for short to ground or power.
  5. 5
    Check the air intake tract downstream of the sensor for cracks or disconnected hoses that could allow unmetered air to enter.
  6. 6
    Inspect the crankcase ventilation system for oil mist; if the sensor tip is oil-coated, clean it and rectify the PCV fault before clearing codes.
  7. 7
    If all wiring and sensor tests pass, perform a PCM input circuit test per manufacturer service data before condemning the control module.

Related powertrain codes

Frequently asked questions

My IAT sensor is integrated into the MAF housing — do I have to replace the whole MAF assembly?

Not always. On some vehicles the IAT element is available as a standalone replacement insert; on others the MAF/IAT is a single non-serviceable unit. Check your parts catalogue — if a standalone IAT sensor is listed, test the sensor in isolation first before replacing the more expensive MAF assembly.

Can oil contamination on the IAT sensor cause P0110?

Yes. Oil mist from an overactive crankcase ventilation (PCV) system coats the thermistor, insulating it and causing it to report a falsely elevated or erratic temperature. Cleaning the sensor tip and fixing the PCV issue will often resolve the code without sensor replacement.

Is P0110 the same as P0112 or P0113?

They are related but distinct. P0110 is a generic circuit malfunction covering any signal fault (stuck high, stuck low, or erratic). P0112 specifically means the signal is continuously low (sensor or circuit shorted to ground), and P0113 means the signal is continuously high (open circuit). P0110 may indicate a fault that does not fit neatly into either of those extremes.

Will P0110 cause the engine to fail emissions testing?

Yes. P0110 stores a MIL-on fault and will flag the OBD readiness monitors as incomplete or failing, which is an automatic fail in most emissions inspection regimes. Additionally, the incorrect air temperature data can cause the fuel system to run rich, raising hydrocarbon and CO emissions.

Disabling P0110 in software

RaceTune can permanently disable P0110 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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