Lost Communication With ECM/PCM B
What does U0115 mean?
The U0115 code means the vehicle's onboard diagnostic system has detected: Lost Communication With ECM/PCM B. This is a critical severity code.
Common Symptoms
- Check Engine Light and multiple warning lights on
- Engine may not start or stall unexpectedly
- No communication with scan tool on some modules
- Loss of various engine functions
- Transmission shifting problems
Probable Causes (Ranked by Likelihood)
- Failed ECM/PCM B processor Very High
- Open or shorted CAN bus wiring to ECM/PCM B High
- ECM/PCM B power supply or ground failure Moderate
- Software corruption in ECM/PCM B Moderate
- Water damage to ECM/PCM B Low
Step-by-Step Diagnostic Procedure
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Attempt communication with ECM/PCM B using a factory-level scan tool
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Check power and ground circuits at ECM/PCM B connector
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Verify CAN bus wiring integrity between ECM/PCM A and B
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Measure CAN bus resistance -- should read approximately 60 ohms
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Check for water intrusion or corrosion at the ECM/PCM B connector
Frequently Asked Questions
Can I drive with code U0115?
No. Lost communication with the secondary ECM/PCM means critical engine functions may be compromised. The vehicle could stall without warning. Have it towed to a repair shop.
What is ECM/PCM B?
Some vehicles use two ECM/PCM processors to handle the engine and powertrain functions. ECM/PCM B is the secondary processor that handles specific functions like fuel injection timing or transmission control.
Is U0115 expensive to fix?
ECM/PCM replacement and programming can cost $300 to $1500. If only a wiring issue is found, repairs may be under $300.