What Does U0115 Mean?
Communication has been lost with the secondary Engine Control Module or Powertrain Control Module B. Some vehicles use dual ECMs/PCMs for redundancy or to manage separate engine banks in V-configuration engines.
Safety Warning
Engine may not start, run rough, or enter limp mode with reduced power. In dual-ECM systems, one bank of cylinders may not function, making the vehicle unsafe to drive at normal speeds.
Common Causes
35%
Wiring harness damage or connector corrosion at ECM/PCM B
30%
Failed ECM/PCM B internal circuit failure
20%
CAN bus network fault or short circuit
10%
Power supply or ground circuit problem to module B
5%
Software incompatibility or corrupted programming
Diagnostic Steps
1
Step 1: Check power and ground circuits to ECM/PCM B; verify proper voltage at module connector
2
Step 2: Inspect all connectors and wiring to module B for physical damage, oil contamination, or corrosion
3
Step 3: Attempt to establish communication with ECM/PCM B using manufacturer-specific scan tool
4
Step 4: Test CAN bus network integrity between primary and secondary control modules
5
Step 5: Check for technical service bulletins; reprogram or replace ECM/PCM B if confirmed faulty
Estimated Repair Cost
$300 - $2,000
Parts + labor, varies by vehicle and location
Communication has been lost with the secondary Engine Control Module or Powertrain Control Module B. Some vehicles use dual ECMs/PCMs for redundancy or to manage separate engine banks in V-configuration engines.
The most common cause of U0115 (Lost Communication With ECM/PCM "B") is: Wiring harness damage or connector corrosion at ECM/PCM B
Typical repair costs for U0115 range from $300 to $2,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may not start, run rough, or enter limp mode with reduced power. In dual-ECM systems, one bank of cylinders may not function, making the vehicle unsafe to drive at normal speeds.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0115 to identify the root cause.
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Quick Info
Category
Network
System
Engine/Powertrain Control
Difficulty
Type
Generic (SAE)
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