View Single Post
  #6  
Old June 15th 18, 03:00 AM posted to rec.autos.tech
Steve W.[_6_]
external usenet poster
 
Posts: 1,161
Default Mazda tribute, 6 circuit codes

wrote:
> I have a 2005 Mazda Tribute 3.0. About a month ago I had the engine
> light come on, I immediately checked the codes. p0443 ( Purge valve
> solenoid ) p0403 ( egr solenoid ) and all 4 o2 sensors p0 135 141
> 155 161. ( o2 heater circuit ) All 6 codes are electrical circuit
> related. I have checked the o2 fuse and it is fine ( replaced it
> anyway ) These parts did not all fail at the same time. I removed
> purge solenoid and energised , it clicked and allowed air to pass
> through it, seems to have no issues. I replaced the egr vacuum
> solenoid, since it is a common failed part. The egr valve itself
> holds vacuum no problem. I tested for 12 volts leading to purge
> solenoid and egr vacuum solenoid. They both have 12 volts. I tested
> between the egr solenoid and pcm for 12 volts, it has 12 volts as it
> should, it is pcm ground side switched. I have not tested the o2
> sensors for power, but I have inspected the wires and they seem ok.
>
> I have checked the PCM harness and the wires seem ok. I have checked
> for vacuum leaks and cannot find any. The car ran fine for weeks
> after the codes were set. It now runs fine until the codes are set
> and then runs rough at idle. I do not drive the car and I will not
> until I can sort the issue. It could be PCM related? I applied a
> vacuum gauge to egr and road tested it. The egr solenoid is opening
> and passing vacuum to egr valve as it should. Apply throttle and the
> solenoid opens egr, let go of gas and immediately no vacuum to egr,
> seems normal to me, yet still the p0403 egr electrical code. I do
> not believe any of the parts are bad, also i cant see bad o2 sensors
> causing a purge valve and egr solenoid electrical codes. I could
> understand a bad egr system causing o2 codes, but not necessarily, o2
> heater circuit codes. I was thinking pcm issues, but seeing the egr
> solenoid seemingly working as it should, passing vacuum to valve,
> that seems to imply pcm is doing as it should, completing the
> circuit. I have power to dpfe sensor as well, not sure how a bad
> dpfe could cause purge code circuit and o2 codes circuit.
>
> I had 58 miles with no codes and all my monitors were ready. CEL came
> on during inspection and all 6 codes were back. they now come back as
> soon as engine is warm.
>
> At a loss here.


Toss a scan tool on it that can read live data. Start with a cold engine
and watch the O2 sensor activity. The description sounds like one of the
heaters is grounding out internally and shutting off the 12 volt feed.
While you watch that you could connect a meter to one of the other 12
volt feeds on that circuit and watch it as well.

The "harder" method would involve pulling the O2 connectors one at a
time and seeing which one only sets a code for itself and not the other
codes. While watching the 12V feed. It's a shortcut but should point out
the issue. You can also do that with the others as well. As you have to
clear the codes and run a drive cycle to get it to pass anyway.

--
Steve W.
Ads