Network, generic

U0502 Invalid Data Received From Door Control Module C

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

For door control module C the letter is a weak guide. In the generic list its lost-communication partner is U0201, yet GM's 2011 Saab 9-5 code list uses U0201 for the transfer case control module. So on some makes the slot is not a door at all, and the vehicle's own fault text decides. Where it does mean a third door unit, the check is the usual one: frames from C arrive, but their content is rejected because a signal is undefined, the alive counter does not step correctly or the checksum fails. Saab sorts such findings into subtypes 71, 72 and 74 after the code. No public bulletin names U0502. Door-related effects, if any, are confined to the door C controls; total loss of contact is U0201.

Likely causes

Door control module C internally faulty

Damaged wiring in the door hinge area

Manufacturer uses this code slot for another module

Symptoms

Lock, window or mirror of one door working only sometimes
Stored code without noticeable fault

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€0–500

Time0.5–3 h

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

Parts involved

door control module c

Related codes

U0201 U0501 U0503

References: saabwisonline.com, patents.google.com.