Q: abs, traction control, E brake and check engine light comes on, code U0121 and U1120 show on scan tool what could be causing it?

asked by on February 21, 2017

I was driving on the express way and out of no where abs, traction control, E brake and check engine light come on the dash board, also the speedometer needle drops to 0 and it would not shift. I shut it off and start it back on and it goes to normal, I drive it for a little bit, and all the lights come back on, the needle drops and It doesn't shift. I scanned it and code U0121 (lost communication with anti-lock brake module) and U1120 (lost wheel distance message) show up. I already checked all abs wheel speed sensor and replaced one, all the lights went off except for check engine light. I drove it, parked it, and wanted to drive it again but all the lights came on again. so I unplugged the abs control module and plugged it back in, I drove it and it was all good ALL the lights went off, but when I connect the scanner it still reads the codes. so do I have to erase the codes with the scanner myself or is the problem still there but just the lights aren't coming on?

My car has 143980 miles.
My car has an automatic transmission.

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Hi there. The only component that impacts the majority of these systems is a transmission speed sensor. In some cases, the sensor will slowly wear out, lighting individual warning lights when trouble codes are stored in the ECU. However, when all of them illuminate at the same time, it’s likely that the wiring harness was damaged somehow. I would first check the speed sensor and harness to make sure they are not causing your warning light issues first. If this is not the problem, I would recommend having all the OBD-II trouble codes downloaded by a professional mechanic as this might give you a better understanding of the root issue.

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