DTC P0110 – Intake Air Temperature Sensor 1 Circuit.

This fault is common on many petrol and diesel engines using an IAT sensor integrated into the MAF sensor or installed on the intake manifold.

✅ DTC P0110 – Intake Air Temperature Sensor 1 Circuit

Meaning

The ECM detects an electrical fault in the Intake Air Temperature (IAT) Sensor 1 circuit.
This usually means:

Open circuit

Short to ground

Short to power

Incorrect reference voltage

Internal sensor failure

🔧 Common Causes

1. IAT Sensor Fault

Sensor open internally

Sensor shorted

Sensor contaminated by oil/dust

2. Wiring / Connector Problems

Broken wire in harness

Loose / corroded connector pins

Rodent damage

Water intrusion in connector

3. MAF Assembly Problem (if IAT is built-in)

Faulty MAF sensor

Shorted IAT element inside MAF

4. ECU Issues (rare)

Faulty IAT input channel

Poor ground or shared ground faults

📊 Expected Values

The IAT sensor is a NTC thermistor (resistance decreases as temperature increases).

Approximate Readings

Intake Temp Expected IAT Voltage Expected Resistance

0°C 4.5–4.8 V 10–12 kΩ
20°C 3.0–3.5 V 2–3 kΩ
40°C 1.5–2.0 V 1 kΩ
80°C 0.5–1.0 V 200–300 Ω

If your scan tool shows -40°C → open circuit
If it shows +140°C → short circuit

🛠 Step-By-Step Diagnostic Procedure

✅ 1. Scan Tool Check

Look at IAT temperature with key ON, engine OFF.

Compare with ambient temperature.

If reading is way lower (-40°C) → open circuit

If very high (120–140°C) → short to ground

If unstable → intermittent wiring fault

✅ 2. Inspect Sensor & Connector

Check for:

Oil contamination

Broken pins

Loose terminal fit

Water inside connector

Clean connector contacts using electrical contact cleaner.

✅ 3. Check Wiring

Using a multimeter:

Check 5V Reference

One wire should read 5V (sometimes 3.3V depending on vehicle).

Check Ground

The other wire must show solid ground continuity (< 0.2 Ω).

Wiggle Test

If temperature changes while wiggling harness → wiring break.

✅ 4. Test Sensor Resistance

Remove sensor and measure resistance at room temp (20–30°C):

Should be 2–3 kΩ.

If infinite → sensor open → replace

If 0–100 Ω → short → replace

✅ 5. Check MAF Sensor (If IAT Built-in)

If the IAT is inside the MAF:

Check MAF output

Check power/ground to MAF

Often replacing MAF assembly solves P0110

✅ 6. ECU Side Check (Rare)

Check continuity from sensor connector to ECU pins.
If wiring OK and sensor OK → ECM input channel faulty.

🧰 Common Fixes

Most common solutions in workshops:

1. Clean or replace IAT sensor

2. Replace MAF sensor (if integrated type)

3. Repair broken wires near connector

4. Clean corroded pins

5. Repair harness near air filter box (very common)

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