Hey everyone, I’m trying to track down what I believe is an electrical issue with my 2013 Mazda3 iGT (2.0L Skyactiv engine). The car has 189,000 miles and has spent its life in the Northeast, so rust and corrosion are pretty severe.

I’m consistently getting two trouble codes:

• U4015
  
• P2503
  

I already replaced both rear wheel speed sensors and the passenger-side bearing hub, which cleared the wheel sensor-related code. However, these two codes persist.

Here’s what I’ve checked so far:

• Battery: It’s brand new and reads between 13.4V–13.6V under load, with no major voltage dips or spikes.
  
• Dashboard lights: The battery light occasionally flashes while driving. The ABS and traction control lights are always on.
  

I’m looking for advice on where to begin troubleshooting next. Any pointers would be appreciated!

 

Welcome to the forum.

trouble codes are used as a starting point to help to resolve problems. Unless you first confirm a suspected part has failed randomly changing it can and often does cause more issues added to the original unresolved one .

 

hey, thanks for the welcome. Nothing was changed at random. Both rear sensors had tone failures & the passenger bearing hub had a pretty severe separation where the sensor mounted to the rear (see photo). Apart from disconnecting the ABS harness and tracing the whole bundle for shorts, I’m not sure where else to look. Curious if anyone else has had similar issues.