Mazda Navajo - Codes 173 and 178

[jas0n]

Working on my friends Mazda Navajo manual 4 w/od... Either a 94, or 95... with over 200k



I test drove it and there is a hesitation at acceleration, ides at 500 and runs just fine at idle and deceleration, I pulled codes and got KoEo codes 173, and 178:

Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S

and

Oxygen sensor not switching - system was rich Left or Front HO2S

Here is my brainstorm.... possible senarios.

1. both o2 sensors are not functioning
2. is the truck simply running rich.
3. does it mean that the first 02 sensor is bad, causing the truck to run rich and causing the rear sensor to read rich....
4. first sensor goes bad, killing catalytic converter, thus killing the last cat

Should I just replace both sensors, are the sensors bad either way? Or is there something further up the line that could cause both not to work.

The exhaust is particularly loud, but could the CAT still be bad?



I certainly appreciate any help. I dont know if this has any value, but he was having other problems and replaced the MAF, which made it run better, could not unplugging the battery after a repair like that make the truck run like this?


thanks,


edit: video got done uploading

 

[jas0n]

the guy is coming back over today for me to help, any ideas?

 

[TexCaliBII]

Seems your on the right track. The upstream O2 can cause the down stream one to go out of range if it is reporting a lean condition when there is not one (rich condition). A bad/blocked cat can mess with this as well. Were it me I'd swap out the first O2 and test. Of course there is also the FPR that can cause a fuel injected engine to run rich if it is indeed running rich. Depending on how long the O2 have been in the truck they could both just be bad. Good luck on your T/S and repair.

 

[jas0n]

thanks for the response... With 200k miles, he wants me to replace the o2's anyways.. I would be doing both right now, but the auto parts place only had one left in stock. This works out tho, because I can see if the first sensor fixes the problem. By the first sensor, I take it you mean the one that isnt tapped into the egr pipe.

I would really appreciate it if you or someone else could contact me. Any contact info you need is in my profile. Ive got AIM, and Yahoo on my phone, I will also put my cell number in my profile here incase someone wants to text me.. I just got done jacking his navajo up, came in to drink something, and now I am going back outside to replace that sensor... Thanks again for the response, I will keep everyone in the loop.


thx,
-jason

EDIT: Added My Cell Number, You can go view my profile and goto the contact info screen, my number will be under the ICQ section. Anyone is welcome to text or IM me to figure this out...