176, 177 and 543 Codes

[ssmoparviii]

Well the check engine light came on today when driving. Got home and hooked the scanner up to the Mark. I got three codes, a 176, 177 and a 543. I know the 176 and 177 are O2 sensor codes but the question I have is the 543. It says its a fuel pump secondary circuit fault. What would cause that? Bad fuel pump? Could it be bad O2's that would cause that? Ive never heard of such a thing. And what is the fuel pump secondary circuit anyways?

 

[chargerxr]

My son's 93 had the same codes. The o2 codes do cause the 543 code to set.

 

[ssmoparviii]

So my question is how many O2's does the Mark have? Is it just one or are there three, maybe four? Im learning this cars EEC system is a cross between OBDI and OBDII.

 

[chargerxr]

If I remember correctly, the 93 thru 95's have 2 and the rest have 4.

 

[marco]

I only seen two on my 94.

 

[ssmoparviii]

Then two it must be!!!

 

[chris2523]

If I remember correctly, the 93 thru 95's have 2 and the rest have 4.

yes.

93-95 is OBD1 with 2 o2s. 96-98 is OBD2 with 4 o2s.

 

[ssmoparviii]

Where on the exhaust system are they located?

 

[chris2523]

just upstream of the cats.
i had to drop the exhaust to change them.

 

[ssmoparviii]

Ya I went out and looked and the pain out weights the cost of doing them. I think I will take it in.

 

[chris2523]

Ya I went out and looked and the pain out weights the cost of doing them. I think I will take it in.

:lol: yeah i understand. it wasn't easy.