Powertrain, generic (extended)

P26C9 Chassis Control Module 2 Requested MIL Illumination

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26C9 is the message slot for a second chassis control module: if module 2 detects an emission-related fault, it can ask the engine module to switch on the check engine lamp, and the engine module records this request as P26C9. No manufacturer documents this code in public. The mechanism is known from its partner P26C8, which GM monitors in its 2018 engine and hybrid tables continuously from three seconds after power-up as Type A without its own lamp request. CARB's OBD rule requires that emission-relevant faults of other control units reach the driver through the MIL, which is why such forwarding codes exist. P26C9 says nothing about the actual defect – only reading the fault memory of chassis module 2 shows what lies behind it.

Likely causes

Emission-related fault stored in chassis control module 2
Incorrect configuration or software after module replacement
Low voltage or network fault corrupting the request message

Symptoms

  • Check engine lamp on
  • Codes stored in a chassis module in addition to the engine 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 2communication bus

Related codes

P26C8P25C9P2561P0700

References: law.cornell.edu, gsi.ext.gm.com.