My 2008 Mazda 6 2.3L just stalled on me yesterday and will not start. I pulled a U0100 code, and after cranking engine a few times battery became so low everything went haywire....relays clicking, guages all over the place....turned out the battery was not just discharged but actually bad. Got new battery and now everything works but engine will start but then stop immediately. Checked all vacuum lines, cleaned MAF sensor, verified all relays and fuses okay. I cleared the engine codes before replacing battery, and after many attempts at starting with new battery checked codes again and still got U0100 code. Maybe the Ecu just needs to get reset or "flashed"? Thanks for any help. Zack. And also the vehicle was in an accident two days before with damage to drivers side fron corner....air bag did not deploy.
Hi there,
This code indicates an issue with the ECM. Here is some info for you.
U0100 MAZDA - Lost Communication With Engine Control Module Read more: https://www.autocodes.com/u0100_mazda.html
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