Powertrain, generic (extended)

P2548 Torque Management Request Input Signal B

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2548 is the general fault on a second torque request channel, B, used when a further module besides the transmission may ask the engine for less or more torque. GM spells out who sits on channel B: in the ECM part of its 2017 table 17OBDG04 and again in 19OBDG03A, P2548 checks the traction torque and speed request coming from the electronic brake and traction control module. A failure is counted when the message's two's-complement protection value does not match, at least 10 of 20 samples, or when the rolling counter fails to step up, at least 6 of 10. The test runs with run/crank active for over 0.5 s, ignition above 6.41 V and no lost-communication code U0121; GM rates it Type B, two trips. Traction or stability intervention via the engine may then be limited. P2549 to P2551 are its narrower faults.

Likely causes

Data bus disturbance between brake module and engine module
Brake/traction control module sends corrupted messages
Weak battery or poor module power supply

Symptoms

  • Check engine light after two trips (GM Type B)
  • Traction or stability control warning lamp
  • Reduced traction intervention on slippery roads

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–800
Time0.5–4 h

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

Parts involved

torque management input babs module

Related codes

P2549P2550P2551P2544U0121

References: gsi.ext.gm.com, gsi.ext.gm.com.