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Module communication

U0115 No communication with the engine control module (ECM) B

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U0115 means: No communication with the engine control module (ECM) B. The car's control modules talk to each other over the CAN bus. Drive gently and have the car checked soon. The most common repair costs about €120–220 in Estonia, depending on make and model.

Is it safe to drive?Get it checked soonDrive gently and have the car checked soon.
Battery replacement€120–220parts and labour in Estonia, depending on make and model

What it means

The car's control modules talk to each other over the CAN bus. One module isn't getting messages from another, or the data it gets is faulty.

What you may notice

  • Several warning lights at once
  • Some function doesn't work
  • The car may not start or may go into limp mode

What could be wrong

  1. 1Low or unstable battery voltage · Battery replacement €120–220
  2. 2Module supply, fuse or ground · Control unit check and software €150–300
  3. 3Broken or corroded CAN wire or connector · Wiring or connector repair €45–90
  4. 4Faulty module or wrong software · Control unit check and software €150–300

Repair difficulty: Moderate

What you can check yourself

Check the battery and terminals first. A great many communication codes appear after a weak battery or a jump start. Best left to a workshop. It needs a diagnostic tool and experience.

How we fix it

  1. We read codes from all modules and see which one isn't answering
  2. We measure the module supply and the CAN bus
  3. We repair the wire or connector
  4. We update the software or replace the module

Standard SAE description: Lost Communication With ECM/PCM "B"

Related symptoms: Loss of power or limp mode

Check the fuse · If a light, the horn, wipers, a socket or the fuel pump is dead, a blown fuse may be the cause.Fuse boxes by car →

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

Book a diagnostic check

Questions

What does fault code U0115 mean?

No communication with the engine control module (ECM) B. The car's control modules talk to each other over the CAN bus. One module isn't getting messages from another, or the data it gets is faulty.

Can I drive with code U0115?

Drive gently and have the car checked soon.

How much does it cost to fix U0115?

It depends on the cause: battery replacement €120–220; control unit check and software €150–300; wiring or connector repair €45–90. Prices include labour at €45/h, depending on make and model.

How is U0115 fixed?

We read codes from all modules and see which one isn't answering. We measure the module supply and the CAN bus. We repair the wire or connector. We update the software or replace the module.

Related codes

U0116No communication with the coolant temperature moduleU0114No communication with the 4WD clutch moduleU0154No communication with the passenger occupant sensor moduleU0155No communication with the instrument clusterU0156No communication with the driver information centre AB1318Battery voltage too low (body module)B1600PATS: key transponder signal not receivedU0118No communication with the fuel additive (DPF) module

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.

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