Need to replace O2 sensors - general advice

J

jrm94mark8

Registered
Hello,

I recently posted the message below and realized it should have gone here in the exhuast forum. I've got 95K and getting check engine codes related to O2 sensors. Just looking for a quick run down on how to replace them, where they are located etc. My tech manual says "threaded into exhuast pipe manifold."
I know there are 2 for this car, correct?

Thanks

*******************************************
Orginal posted message

#13599, "Check engine codes retrieved - advice please"

I recently purchased an innova tester to read the check engione codes onmy 1994 Mark 8. I posted about it a while back and finally have them retrieved and want to get advice. A little background first. I get the check engine code only on the highway or if I really wind the car out and get the rpm's up. I had them read a while back by a mechanic and it was throwing 3 codes - 02 sensors and a fuel one - can't remeber exactly. Anyway - he told me I had an intake leak and thought thought could be a culprit....allowing too much cool air in and throwing codes. I had that fixed and the check engine light came back. I didn't go back there and got this reader. So - I just read the codes and this is what it is telling me alog with the code descriptions in the code readers book.

172 HEGO (H02S) sensor fault/lean
176 HEGO (H02S) sensor fault/always lean
177 HEGO (H02S) sensor fault/always rich
524 Low speed fuel pump circuit open - battery to ECA
543 Fuel pump secondary circuit fault

I'm defintiely thinking the 02 sensors but not sure if the fuel ones are being thrown because of the 02? Anyone seen this or have advice? Should I replace 02 sensors, clear codes, and test again? Anything I should be worried about? The car runs great but is a bit tought to start in the cold and the idle isn't as smooth as it once was.

Thanks for any help-
 
RE: Need to replace O2 sensors - general advice

[div class="dcquote"][strong]Quote[/strong]
Hello,I recently posted the message below and realized it should have gone here in the exhuast forum. I've got 95K and getting check engine codes related to O2 sensors. Just looking for a quick run down on how to replace them, where they are located etc. My tech manual says "threaded into exhuast pipe manifold."I know there are 2 for this car, correct?Thanks*******************************************Orginal posted message#13599, "Check engine codes retrieved - advice please"I recently purchased an innova tester to read the check engione codes onmy 1994 Mark 8. I posted about it a while back and finally have them retrieved and want to get advice. A little background first. I get the check engine code only on the highway or if I really wind the car out and get the rpm's up. I had them read a while back by a mechanic and it was throwing 3 codes - 02 sensors and a fuel one - can't remeber exactly. Anyway - he told me I had an intake leak and thought thought could be a culprit....allowing too much cool air in and throwing codes. I had that fixed and the check engine light came back. I didn't go back there and got this reader. So - I just read the codes and this is what it is telling me alog with the code descriptions in the code readers book.172 HEGO (H02S) sensor fault/lean176 HEGO (H02S) sensor fault/always lean177 HEGO (H02S) sensor fault/always rich524 Low speed fuel pump circuit open - battery to ECA543 Fuel pump secondary circuit faultI'm defintiely thinking the 02 sensors but not sure if the fuel ones are being thrown because of the 02? Anyone seen this or have advice? Should I replace 02 sensors, clear codes, and test again? Anything I should be worried about? The car runs great but is a bit tought to start in the cold and the idle isn't as smooth as it once was.Thanks for any help-
[/div]

Looks like only one is giving a code, but it's always best to replace them in pairs. One of the sensors is very difficult to replace; if you can spare $70 each (parts & labor) to replace them, do it. Even with air tools, it's a frustrating job.
 
RE: Need to replace O2 sensors - general advice

Thanks, I plan on doing them in pairs. If you do know where they are and could point me in the right direction that would be great. I have a freind who is a great mechanic and does all the work on his cars. Before I take it in I'm pretty sure he can help me replace them but needa startin gpoint.

THanks-
 
RE: Need to replace O2 sensors - general advice

Damn!! Thanks alot for the photo. That does look like a tricky spot to get at.

JRM
 
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