Powertrain, generic (extended)

P2D88 Fan 1 Control Module Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P2D88 means the electronics of fan 1 do not behave as expected although supply and communication are present: the module reports an internal fault, or the speed it sends back does not fit the request. Audi documents the code for 2025 Q5, Q5 Sportback, SQ5 and SQ5 Sportback in TSB 2081184/1. The thermal management control unit stores P2D88, P2D8B or the LIN error U366500, the engine warning lamp comes on and the air conditioning may stop. The reason was an incorrectly fitted ground of the electric fan at earth point 642 on cars built before 28 May 2025; the workshop inspects and reworks it. A Hyundai patent shows the principle behind such checks: the fan controller returns its measured speed to the engine unit and falls back to fixed duty values when the link fails. Fan 2 has P2D8B.

Likely causes

Poor or wrongly fitted ground connection of the fan

Internal fault of the fan control electronics

Fan blocked or slowed by debris or bearing wear

Moisture or corrosion in the fan connector or LIN line

Symptoms

Engine warning lamp on
Air conditioning stops cooling
Fan does not run or runs irregularly

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–800

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fan control module 1wiring harnessecm

References: static.nhtsa.gov, patents.google.com, law.cornell.edu.