Last week my engine light went on. 2005 Tribute 3.0 ( po135 po141 po155 po161 ) o2 sensor heater circuit codes. I also got a po403 and a po443. The 403 is egr circuit and the 443 is purge valve circuit. I find it hard to believe they all went at once. I checked the engine fuse for the 02 heaters, I checked all the connections at EGR etc. What do the 02 egr and purge all have in common? I am hoping it is not the ECM if that is even possible for the ECM to fail all at once for 3 sets of issues. I'm at a loss and i don't want to just start part swapping.

 

Check the fuse in the engine compartment fuse box. Don't recall which number but it's one of the smaller ones towards the front of the car... It'll be the one that reads open :-)

 

all fuses are good

 

my readiness monitors show the 02 sensor as ready as well as 02 heater as ready, egr as ready. I have 2 incomplete monitors, catalyst and evap. Would a monitor be ready if a part was bad, could my 02 sensors show as ready if they were bad?

 

P0135 H02S-11 Bank 1 Sensor 1 Heater circuit
P0141 H02S-12 Bank 1 Sensor 2 Heater circuit
P0155 H02S-21 Bank 2 Sensor 1 Heater circuit
P0161 H02S-22 Bank 2 Sensor 2 Heater circuit

P0403 EGR Solenoid
P0443 Purge solenoid valve

What happens when you clear the codes?
Are you able to read live data with your code reader?
When did the PCM software last get updated by Mazda?
Does the engine misfire or hesitate?

Check for power & earth at each sensors wiring plug for the heater circuit. Power & earth both come direct from the PCM

 

when I clear the codes, they stay away for awhile and come back. I have checked for obvious wire breaks and damage. I have checked the sockets and cleaned them all. I have checked the wiring at 3 of the 4 o2 sensors. I feel I have a low idle when the car gets warmed up and driven for awhile. After I clear the codes I have been watching the readiness monitors. so far the o2 monitor, the o2 heater monitor, the egr monitor are ready. Can they be ready and still have an issue? I would think not, but I am not sure. I have evap monitor and catalyst monitor incomplete. I suspect when the evap monitor is ready, it will throw all the codes again. Since the egr monitor is ready, that leaves the purge valve solenoid as my suspect. Could a bad purge valve throw all the six codes I get? They do all share the same fuse, I have pulled the 15 amp fuse in engine and it gives me all 6 codes again, I put the fuse back in and they are gone.

My code reader can read errors and monitors only, its a cheap actron pocket scan.

 

still have the issue, I posted this on another forum......

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.

 

It was the PCM, all fixed now

 

Thanks for letting us know
it is good to get some resolution which may help others