P0127: Intake Air Temperature Too High (Meaning, Causes, Fixes)
What P0127 means
The engine computer (PCM) uses the intake air temperature (IAT) sensor together with the mass airflow (MAF) sensor to work out how much fuel to inject and how to set ignition timing. P0127 is a generic OBD-II code defined as 'Intake Air Temperature Too High'. OBD-Codes.com says it sets when the PCM detects an IAT sensor signal indicating that the temperature or the circuit voltage is higher than the maximum allowable limit. The IAT sensor is usually a two-wire temperature sensor in the air inlet pipe or air cleaner box, sometimes threaded into the intake manifold or built into the MAF sensor housing. RepairPal describes it more simply: the PCM sets P0127 when it detects a problem with the IAT sensor or its circuit. The sources differ on severity (OBD-Codes.com says severe, RepairPal says Moderate) and on causes: OBD-Codes.com lists air intake problems such as a clogged air filter, broken inlet pipe or faulty MAF sensor, while RepairPal lists a failed PCM, which OBD-Codes.com does not mention. Exact limits and sensor locations vary by make and model.
Severity: can I keep driving?
Drive with caution, fix soon
Get it checked soon. The two sources disagree on how serious it is: OBD-Codes.com says P0127 should be considered severe because the engine computer uses the intake air temperature to set fuel delivery, while RepairPal rates it 'Moderate', meaning it may not threaten safety right away but should be diagnosed within a reasonable time. The car usually still drives, but expect hesitation or weaker performance until it's fixed.
Common symptoms
- Check engine light on
- Hesitation or surge at idle or on light acceleration (listed by OBD-Codes.com)
- Decreased engine performance, especially on a cold start
- Lower fuel economy
- Other driveability codes may also be stored (per OBD-Codes.com)
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- IAT sensor left unplugged, often after an air filter check or replacement
- Open or shorted IAT sensor wiring or connectors, including corrosion
- Faulty intake air temperature sensor
- Faulty mass airflow (MAF) sensor, especially where the IAT is built into it (listed by OBD-Codes.com)
- Clogged air filter (listed by OBD-Codes.com)
- Broken air intake inlet pipe (listed by OBD-Codes.com)
- Engine computer (PCM) failure (listed by RepairPal)
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- If the air filter was recently serviced, check that the IAT sensor (or the MAF sensor it's part of) is plugged back in. OBD-Codes.com says this is a common cause. Reconnect it, clear the code and drive normally.
- Check for technical service bulletins (TSBs) for your vehicle before replacing parts.
- Inspect the air filter, air box and inlet pipe for clogging, cracks or loose clamps.
- Inspect the IAT sensor connector and wiring for corrosion, damage or loose pins. OBD-Codes.com notes the connector is prone to corrosion because it's often near the battery and coolant reservoir.
- With a scan tool, compare the IAT reading against the actual intake air temperature measured with an infrared thermometer. A reading far off from reality points to the sensor or its wiring.
Typical fixes
- Reconnect an unplugged IAT or MAF sensor connector
- Repair open or shorted IAT wiring or a corroded connector
- Replace a faulty IAT sensor (or the MAF sensor if the IAT is built in)
- Replace a clogged air filter or repair a broken intake inlet pipe
- Repair or replace the PCM only after the sensor and wiring test good
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- The code returns after the sensor is plugged in and the wiring looks fine
- OBD-Codes.com recommends testing the sensor's resistance and output voltage against the manufacturer's temperature-to-voltage chart with a digital multimeter, then checking for a 5-volt reference and a good ground at the connector
- If reference voltage and ground are missing, the open or shorted circuit needs tracing with the related modules disconnected
- RepairPal lists PCM failure as a possible cause, which a shop should confirm only after ruling out the sensor and wiring
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Can I drive with P0127?
Usually yes for a short while, but get it checked soon. RepairPal rates it Moderate, while OBD-Codes.com calls it severe because the engine computer uses intake air temperature to set fueling. Expect hesitation, weaker performance or higher fuel use until it's fixed.
I just changed my air filter and now have P0127. Why?
OBD-Codes.com says the IAT sensor is often left disconnected when the air filter is checked or replaced. Reconnect the sensor (on many cars it's part of the MAF sensor), clear the code and drive normally.
Is P0127 always a bad sensor?
No. Both sources list wiring problems, and OBD-Codes.com also lists a clogged air filter, a broken inlet pipe or a faulty MAF sensor. Compare the scan tool reading with the real air temperature before buying a sensor.
What's the difference between P0127 and P0113?
Both involve the intake air temperature sensor. P0113 is 'Intake Air Temperature (IAT) Sensor 1 Circuit High', an electrical circuit code, while P0127 is defined as 'Intake Air Temperature Too High'. They share many causes, like wiring and a faulty sensor, so check both if they appear together.
Sources
Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.