Check engine light with code U034B after recall for battery replacement and software update 2021 Big Bend

[Susanne Smith]

Ever since the recall for a new battery and software update on our 2021 Bronco Sport Big Bend, we have been getting check engine light with code U034B popping up. Took it to dealer and they could not identify any problem. This issue seems to only be happening after going over bumpy areas (i.e. railroad tracks, rumble strips, etc.) Vehicle went into limp mode one time and after about 20 minutes was able to restart and limp mode was gone. Anyone else had this type of problem and/or been able to resolve the issue. Thank You

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[jkernitzki]

Could just be a loose battery terminal connection. That it happened after a battery replacement and only occurs when encountering bumps lends me to think that's the most likely cause. The U034B can be triggered by bad connections even though it's not directly pointing to the source fault.

 

[Susanne Smith]

Could just be a loose battery terminal connection. That it happened after a battery replacement and only occurs when encountering bumps lends me to think that's the most likely cause. The U034B can be triggered by bad connections even though it's not directly pointing to the source fault.

 

[Susanne Smith]

I had a suspicion that this might be a problem so made sure all of the battery connections were tight. U034B popped up again. Could it possibly be a bad ground connection in the AWD module? Thanks for your response.

 

[jkernitzki]

I had a suspicion that this might be a problem so made sure all of the battery connections were tight. U034B popped up again. Could it possibly be a bad ground connection in the AWD module? Thanks for your response.

I’d have the battery tested. I know it’s new, but that’s no guarantee of performance. Could also be an internal defect in manufacture.

Bad grounds seem to also be a recurring theme.

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