Mazda tribute, 6 circuit codes

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 ) p
0403 ( egr solenoid ) and all 4 o2 sensors p0 135 141 155 161. ( o2 heate
r 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 t
he egr vacuum solenoid, since it is a common failed part. The egr valve its
elf holds vacuum no problem. I tested for 12 volts leading to purge soleno
id and egr vacuum solenoid. They both have 12 volts. I tested between the e
gr solenoid and pcm for 12 volts, it has 12 volts as it should, it is pcm g
round 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 va
cuum 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 vacu
um 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 cau
sing a purge valve and egr solenoid electrical codes. I could understand a
bad egr system causing o2 codes, but not necessarily, o2 heater circuit co
des. I was thinking pcm issues, but seeing the egr solenoid seemingly work
ing 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 circu
it.
I had 58 miles with no codes and all my monitors were ready. CEL came on d
uring inspection and all 6 codes were back. they now come back as soon as e
ngine is warm.

At a loss here.
Reply to
karlniemi3rd
:
t 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 hea ter circuit ) All 6 codes are electrical circuit related. I have checke d the o2 fuse and it is fine ( replaced it anyway ) These parts did not al l fail at the same time. I removed purge solenoid and energised , it click ed 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 i tself holds vacuum no problem. I tested for 12 volts leading to purge sole noid 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 ha ve inspected the wires
vacuum leaks and cannot find any. The car ran fine for weeks after the cod es were set. It now runs fine until the codes are set and then runs rough a t idle.
ld be PCM related? I applied a vacuum gauge to egr and road tested it. Th e egr solenoid is opening and passing vacuum to egr valve as it should. App ly throttle and the solenoid opens egr, let go of gas and immediately no va cuum 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 c ausing 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 wo rking as it should, passing vacuum to valve, that seems to imply pcm is doi ng as it should, completing the circuit. I have power to dpfe sensor as we ll, not sure how a bad dpfe could cause purge code circuit and o2 codes cir cuit.
during inspection and all 6 codes were back. they now come back as soon as engine is warm.
Check your idle air control valve.
Reply to
dsi1
:
Forget about the codes, your idle could be a separate problem. I recently h ad a trouble code indicating that my throttle sensor was bad, changing it d idn't solve the problem but replacing a part in the steering column did. If you are having a problem with the idle, the idle air control valve should be the first place you look. Take it off, clean it, and make sure it works.
Reply to
dsi1
Thanks for the reply. I replaced the PCM a year ago for the well known issu e of plugs and coils burning up the pcm. I replaced pcm and plugs and coils with recommended parts. While doing so, the throttle body, intake manifold , egr, and IAC were thoroughly cleaned. I will revisit the IAC.
I understand that codes do NOT always point to the true problem. I could se e o2 codes being caused by other emission issues etc. My o2 codes are heate r circuit failure codes, my egr code is circuit failure codes, along with t he purge solenoid circuit failure codes. The idle issue when codes set seem to feel like when the egr has vacuum at idle. I had it happen close to hom e and pulled in driveway, yanked the egr hose and it settled right back to normal. i am not sure if there was vacuum or egr was stuck open a tad. Eith er way that in itself should not trigger circuit failure codes.
I am trying to find the common denominator of the circuit codes. the purge and all 4 02's share the same fuse and power wires. I have tested power to be ok. As you know it needs drive cycles to trip the codes, making testing trickier. I road tested egr and it was opening and closing just fine, that makes me feel I cant just assume pcm is shot.
Reply to
karlniemi3rd
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.
Reply to
Steve W.
Thanks Steve, I will keep that in mind. I have another question regarding P CM and readiness monitors. If my pcm was the cause of these issues, lets sa y the drivers that ground the o2 heater circuits are damaged in the pcm..wo uld my o2 heater monitor still complete? My egr, and o2 monitors are compl ete and ready. would that be possible with a damaged pcm?
Reply to
karlniemi3rd
According to Pat Goss, the well-respected auto technician, connecting the scan tool is the last thing one should do in diagnosing an auto malfunction(s). I'm fairly certain I know what he means. Sincerely,
Reply to
J.B. Wood
People that have no diagnostic skills and have never worked on automobiles should not pick up a wrench or a OBD scanner and start monkeying around with them. That just leads to utter confusion.
Reply to
dsi1
That's how we did it back in the old days. Counting flashes. That wasn't mu ch help back then either.
Yesterday I was checking my daughter's Cherokee. That thing is more busted than not. It has an intermittent rough idle. I grabbed the idle control val ve to check the electrical connection and it started getting rough. I grabb ed the body of the valve and applied sideways pressure which caused the idl e to go rough. I suspect that the electrical connection is okay but the uni t itself has to be cleaned or replaced. The good news is that I can buy one dirt cheap on eBay. My target price is less than $10.
Reply to
dsi1
I'd look for cracks in the valve but more importantly cracks in the air plenum and hoses that cause an intermittent vacuum leak when it moves around. --scott
Reply to
Scott Dorsey
Vacuum hose leaks was the first thing I checked. I saw nothing obvious. Aft er that, I checked the idle air control valve. I shall take it out and clea n it. If that does not solve the problem, I'll have to look more carefully for leaks. After that I'll check the ignition system. My guess is that it's the IAC valve. Easy peasy.
Reply to
dsi1

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