P0127: Intake Air Temperature Too High

What it means

The control module monitors intake air temperature and sets this code when the reading exceeds its calibrated limit under the conditions checked. The reading may reflect genuinely hot intake air or an inaccurate sensor signal.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The intake air temperature sensor reports the temperature of air entering the engine, and the module uses that reading to adjust fueling and, on boosted engines, may limit boost. P0127 sets when the reported intake air temperature exceeds the calibrated limit under the conditions being monitored, whether from genuinely hot intake air or a faulty sensor signal.

Common causes

Most likely first.

1. Excessively hot intake air from high underhood or ambient temperatures
2. Restricted airflow through the charge air cooler
3. Charge air cooler or intake air temperature sensor fault
4. Wiring or connector problem

Symptoms

• Check engine light on
• Reduced engine power or boost
• Sluggish acceleration
• Possible reduced fuel economy

How to diagnose it

1. Review freeze-frame data and compare intake air temperature with ambient temperature and other air temperature readings under similar conditions.
2. Inspect the intake ducting and, if fitted, charge air cooler for blockage, damage, restricted airflow, or heat exposure.
3. Check the intake air temperature sensor and connector for looseness, corrosion, contamination, or wiring damage.
4. Monitor the sensor reading as the engine warms and under changing airflow to see whether it responds plausibly.
5. Test the sensor and its circuit against the manufacturer's specification if the reading remains implausible.

Common fixes

• Remove an airflow obstruction from the intake or charge air cooler.
• Repair damaged intake ducting or charge air cooler components that restrict airflow.
• Clean and secure the sensor connector or repair damaged wiring.
• Replace the intake air temperature sensor if its reading fails testing.

Can I keep driving?

The module may reduce power or boost, so allow for slower acceleration and avoid hard acceleration or towing until the cause is known. Stop if engine temperature warnings appear or power loss makes the vehicle unsafe.