P026A

What it means

P026A means the charge air cooler (intercooler) is not cooling the intake air as effectively as the engine control unit expects. The control unit compares the temperature of the boosted air after the cooler with the temperature before it, or with a modelled value, and sets the code when the drop in temperature is too small. The sensors fitted and the exact test used vary by model and engine.

Symptoms

• Loss of power, especially under boost or on a long hill
• Engine management light on, possibly with the car in limp mode
• Higher than normal intake air temperatures on live data
• Poorer fuel economy
• Whistling, hissing or fluttering noise under acceleration if a boost leak is present
• Oil or dampness around intercooler pipes and joints

Possible causes

• Intercooler core blocked on the outside with debris, dirt, insects or bent fins, restricting airflowlikely
• Boost leak from a split charge pipe, loose clip, perished hose or damaged intercooler end tanklikely
• Internal contamination or restriction of the cooler from oil residue or debrispossible
• Faulty or inaccurate intake air temperature or charge air temperature sensor, or its wiring or connectorpossible
• Missing or damaged air ducting, undertray or shrouds that normally direct air through the coolerpossible
• Cooling fan or water pump fault on water-cooled charge air cooler systemspossible
• Faulty control unit or outdated software where a known fault exists for that modelrare

How to diagnose

1. Read stored and pending codes and freeze frame data, noting engine load, speed and air temperatures when the code set
2. Look for other related codes such as boost pressure, intake air temperature or turbo codes, and deal with those first
3. Visually inspect the intercooler, its fins and the airflow path for blockage, damage, missing ducts or oil leaks
4. Inspect all charge pipes, hoses and clamps for splits, looseness and oil misting, and carry out a boost leak test
5. Check the wiring and connectors of the intake and charge air temperature sensors for damage, corrosion or poor contact
6. Compare live temperature readings from the sensors with each other and with ambient temperature on a cold engine to check plausibility
7. Road test while logging air temperatures before and after the cooler under load and look for a poor temperature drop
8. On water-cooled systems, check coolant level, pump and fan operation against the manufacturer's procedure

How to fix

• Clean the intercooler externally and straighten or replace it if the fins are badly damaged
• Repair or replace leaking charge pipes, hoses, clamps or end tanks
• Replace the intercooler if it is internally blocked, contaminated or leaking
• Replace a faulty temperature sensor or repair its wiring and connector
• Refit or replace missing or damaged ducting and shrouds
• Repair the pump, fan or coolant circuit on water-cooled systems, or apply a manufacturer software update if a known calibration fault is confirmed

Can I keep driving?

Nearby codes

• P0269GenericCylinder 3 Contribution/Balance
• P026BGenericInjection Timing Performance