2004 to 2020 Mazda 3 Forum and Mazdaspeed 3 Forums banner
1 - 3 of 3 Posts

· Registered
7 Posts
Discussion Starter · #1 · (Edited)
Hello fellow Mazda 3 enthusiasts.

A little background (TMI):
  • Few months ago my wife said the car felt slow, hard to pass other cars.
  • Got a P013A fault code. Stupidly threw a new part at it thinking that would fix it. The downstream sensor was welded in there pretty good, so I bought the part but gave up and let a mechanic throw it in for me.
  • Replaced tires (weather worn, cracked).
  • Took a long 9 hour trip.
  • On the way home, the check engine and traction control lights started flashing due to a misfire (P0304). I determined that the cylinder 4 ignition coil was shot. I did this by moving the coil, and the problem followed it. Of course it was Labour Day and NAPA was closed bahh. Of note there is a TSB for newer MZ3 (01-014/16), and funnily enough the diagnostic procedure is the same thing I did.
  • Replaced coil.
  • Got home, felt fine the whole way.
  • Weeks later I got a P0140 code. But strangely the sensor was outputting a signal (verified with Torque).
  • Replaced all ignition coils, all spark plugs, cleaned MAF and cleaned throttle body.
  • P013A came back.
  • Now I've done some digging, and turns out there is a TSB for this issue!!!! 01-004/14 says to upgrade the PCM to 88.04. Previous owner had the car in for TSB 01-019/13 (headlight flicker) which updated the PCM to 85.04, so I'm expecting mine is missing the 88.04 update.
Not really sure the point of this post. I guess just looking for feedback on the P013A fault and my other issues, anyone else have this issue? Fix it with a PCM update? Why did my ignition coil fail, possibly another issue? Spark plugs looked pretty good when I had them changed, but did it anyway (9/16" socket btw).

Couple other things I'm concerned about: intake build up and pre-cat health. For the intake, thinking I'll try Seafoam, and I wanna measure the back pressure to see how the cat health is. Ideally the PCM update resolves my problem though...

Anyone ever remove their pre-cat? Was thinking having a shop literally cut it out and put in a straight pipe (province doesn't care about emissions), my concerns would be about the downstream O2 sensor and whether or not it would care.

Also the throttle body noise?? Like a humming sound, cleaning it was a little annoying with it whining away. Also makes the sound when the engine turns off. Worth replacing? Read it is somewhat expected behaviour.

Thanks in advance!

1 - 3 of 3 Posts