U0077Control Module Communication Bus E Off
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- At GM, Bus E is usually a chassis-side network. In the 2018 tables for the LYX engine variant, the ECM watches it the same way as Bus A, more than five bus-off events within 0.81 s, but rates the result Type X without MIL; the transmission's default-to-park checks stay disabled while U0077 is set. On the 2015 Escalade, high resistance under the sill plates in circuit 5986, which wakes the modules for communication, left the brake, steering and suspension modules without a proper wake-up signal; on 2010-15 Equinox and Terrain models corrosion in connector X411 behind the fuel tank caused it. Volvo mild hybrids may store U007700 in the medium-voltage battery module together with P0A7B at pre-delivery; Volvo advises clearing it and reloading software only if it returns with MIL.
- What you may notice
- Service ABS, StabiliTrak or power steering messages
- Suspension or all-wheel-drive warnings
- Heavy steering when the steering module drops off
- Likely causes
- LikelyCorroded underbody connector in the Bus E harness
- PossibleHigh resistance in the communication enable (wake-up) circuit
- RareOne-off software event in a module, cleared without repair
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.