Powertrain, generic (extended)

P26C8 Chassis Control Module 1 Requested MIL Illumination

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26C8 is not a fault of the engine module itself. It is stored when a unit outside the powertrain, which the manufacturer designates chassis control module 1, has logged an emission-related code of its own and asks the engine module over the network to light the check engine lamp. GM lists it in the engine tables 18OBDG04 and in the hybrid tables 18OBDG01: the request message is watched continuously from three seconds after power-up, and the code is Type A but carries no lamp request of its own. GM preliminary information PIT6010 (Buick LaCrosse, Cadillac XT5 2017–2019) mentions P26C8 together with U135A after a transmission range control module was replaced and its software did not match. The real cause is found in the memory of chassis module 1, which has to be read first.

Likely causes

Emission-related fault stored in chassis control module 1
Replaced module with mismatched or missing software configuration
Low supply voltage or network disturbance during start-up

Symptoms

  • Check engine lamp on
  • Service transmission or chassis warning message
  • Additional codes stored in the chassis module

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–1,500
Time0.5–3 h

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

Parts involved

chassis control module 1communication bus

Related codes

P26C9P25A2P25C9P0700

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.