OBD-II trouble code
P0110: Intake Air Temperature Sensor Circuit Malfunction
The PCM has flagged a general fault in the intake air temperature (IAT) sensor circuit — the signal is present but not behaving the way a healthy thermistor should. On a surprising number of engines, the IAT element lives inside the mass airflow sensor, which is why this code so often ends up being a MAF job.
Quick facts
- System
- Powertrain
- Category
- Sensors / Air Intake
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $80 – $400
- DIY difficulty
- Beginner DIY
What does P0110 mean?
P0110 is the broad, catch-all fault for the intake air temperature sensor circuit. Where P0112 and P0113 point specifically at a signal that's pinned too low or too high, P0110 sets when the PCM decides the circuit isn't working correctly without the failure landing cleanly in one of those buckets. The first thing worth knowing is structural: on a large share of modern engines the IAT sensor isn't a standalone part at all — it's a second thermistor built right into the mass airflow (MAF) sensor housing that sits between your air filter and throttle body. That single fact explains why an 'air temperature' code so often turns into a MAF sensor replacement, and why it pays to identify which design your engine uses before you buy any parts.
The IAT sensor is a thermistor — a resistor whose value changes with temperature. Cold air raises its resistance, warm air lowers it, and the PCM reads the resulting voltage to know how dense the incoming air is. That number feeds fuel trim, spark timing, and cold-start enrichment. When the PCM can't trust the IAT signal, it substitutes a default value and keeps running, so the engine rarely feels broken. What you tend to get instead is slightly worse fuel economy, a marginally rougher cold start, and a guaranteed emissions-test failure until the code is cleared.
Because P0110 is electrical rather than mechanical, the usual suspects are the sensor element itself, a corroded or backed-out connector pin, a chafed signal wire, or — on combo units — a MAF assembly that's starting to fail as a whole. It's one of the lower-stakes codes you can get, but it's worth fixing both for the emissions hold and because a bad air-temp reading can quietly cost you a couple of miles per gallon.
Common causes
- Failed IAT thermistor element (standalone sensor)
- Failing MAF/IAT combo unit on engines where the two share a housing
- Corroded, backed-out, or bent pin in the IAT connector
- Chafed or broken signal/ground wire between sensor and PCM
- Connector left unplugged after air-filter or intake work
- Water or oil intrusion in the connector after an engine-bay wash or a soaked air filter
- Aftermarket cold-air intake with a poorly seated sensor port
- Rodent damage to the harness near the air box
Symptoms
- Check engine light on with P0110 stored
- Slightly harder cold starts
- Small drop in fuel economy
- Brief hesitation in the first minute of a cold drive on some engines
- Normal idle and driveability once warm — most owners notice nothing else
- Emissions / smog test failure
Diagnostic steps
- 1.First, determine whether your engine uses a standalone IAT sensor or a combined MAF/IAT housing. This changes both the diagnosis and the cost.
- 2.Pull live data at key-on and compare the IAT reading to the coolant temperature reading. On a cold engine that's sat overnight, the two should read close to each other and close to ambient. A wildly off IAT value points at the sensor circuit.
- 3.Unplug the IAT (or MAF) connector and inspect for green corrosion, pushed-back pins, or moisture in the cavity.
- 4.Check resistance across the sensor terminals and compare to the temperature/resistance spec for your vehicle — a reading that's open or way out of range confirms a bad element.
- 5.Back-probe the signal and ground wires at the sensor while wiggling the harness to expose intermittent opens.
- 6.On combo housings, if the connector and wiring check out, the MAF/IAT assembly is the likely culprit.
Repair cost
$80 – $400
A standalone IAT sensor is the cheap end — roughly $20-$90 in parts and 0.4-1.5 hours of labor, so a shop visit usually lands around $80-$200. The bill climbs to $250-$400 when the IAT is integrated into a mass airflow housing, since you're replacing the whole $150-$350 MAF assembly. A corroded connector or a single chafed wire is the cheapest outcome of all if a technician catches it first.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with intake air temperature sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is a beginner-friendly repair. Common hand tools, a free afternoon, and a willingness to follow a procedure are usually enough. The risk of causing a bigger problem is low if you read up on your specific vehicle first.