P026A: Charge Air Cooler Efficiency Below Threshold

What does P026A mean?

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.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Loss of power under load or in heat
• High intake air temperature in live data

Common causes

• High Charge air cooler clogged on the outside (insects, leaves, dirt) or fins damaged
• High Coolant-cooled cooler: pump faulty, air in the low-temperature circuit, low coolant
• Medium Charge air or ambient temperature sensor inaccurate
• Low Charge air cooler bypass stuck open
• Low Software or calibration

Likelihood is a general estimate across vehicles; your make and model may differ.