P026ACharge Air Cooler Efficiency Below Threshold
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P026A means the charge air cooler is not cooling enough. The module compares the temperature drop across the cooler with the maximum possible (inlet minus ambient) or with a model: GM's 6.6 litre LML diesel sets it below 25 % efficiency, later GM diesels below 50 %, both after two trips; Ford's 6.7 and 3.0 diesels when the measured temperature is 18–35 °C (3.0: 35–65 °C) off the model over about 10 s. GM's 3.0 twin-turbo petrol with a coolant-cooled charge air cooler sets it in the first trip when manifold air exceeds 110 °C or boost has been limited for a long time. Hot intake air costs power and raises NOx and soot.
- What you may notice
- Check engine light on
- Loss of power under load or in heat
- High intake air temperature in live data
- Likely causes
- LikelyCharge air cooler clogged on the outside (insects, leaves, dirt) or fins damaged
- LikelyCoolant-cooled cooler: pump faulty, air in the low-temperature circuit, low coolant
- PossibleCharge air or ambient temperature sensor inaccurate
- RareCharge air cooler bypass stuck open
- RareSoftware or calibration
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.