OBD-II code · Network
U0115 Lost Communication with ECM/PCM "B"
The ECM/PCM "B" has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages. A second engine/powertrain controller is unreachable, which can prevent the engine from running. Typical causes are loss of power or ground at the module, an open or shorted CAN/LIN bus wire, a connector fault, or an internal module failure.
Is it safe to drive with U0115?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelySecondary ECM unpowered
- PossibleCAN wiring to secondary ECM broken
- Less likelyGateway module routing CAN messages incorrectly
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–8 h
- Emissions test
- Likely to fail
- Parts involved
- Ecm, Can Bus Wiring
Related codes
- U0100Lost Communication with ECM/PCM "A"
- U0112Lost Communication with Battery Energy Control Module "B"
- U0113Lost Communication with Battery Charger A Control Module
- U0114Lost Communication with 4WD Clutch Control Module
- U0116Lost Communication with Steering Effort Control Module
- U0117Lost Communication with Drive Motor Control Module 2
- U0118Lost Communication with Cabin Air Quality Sensor Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.