OBD Codes P0117, P0171 & P0057

[therris]

03 Protege is due for an inspection this month and low and behold the CEL pops on. OBD knocked back the above codes.

Any experience out there with these 3 popping up at the same time?

Car runs as it always has. Didn't notice any difference before compared to after.

I assume fixing one of the codes would prolly fix the others, but I'm not sure which one(s) to start with.

Comments welcomed. Thanks for your help.

 

[pcb]

It looks like your coolant temperature sensor might be dead causing the other two codes ( second o2 sensor heater circuit, system too lean).

Check the wires and connections to your coolant temperature sensor.

Section 01-2b-40 of the fsm (factory service manual)

 

[therris]

Will do. Thanks.

 

[thuzil]

As far as I know the coolant temp probe circuit has no feedback to the O2 sensors. As far as I can say, you need a new coolant temperature sensor, and two new O2 sensors.

I have a temp sensor ready to ship if you want.

 

[pcb]

I was thinking if the ECU didn't have proper coolant temperature data it might lean out the fuel air mixture causing the other two codes.

I think you should fix your coolant sensor circuit first, clear the codes, then see if the other two codes come back.

 

[therris]

Thanks for the help. I bought a ECT from Autozone today and installed it. We'll see if the light comes on again tomorrow. My voltmeter disappeared so I can't check to see if my old one was faulty.

Thanks for the help and I'll keep ya'll posted.

 

[therris]

No dice on the ECT sensor. Looks like I've got a spare now. Drove the car around the house right after install yesterday. Got in this morning and the CEL came right on. Guess I'll check the O2 sensors next.

 

[therris]

BTW, is there a suggestion on which o2 sensor I should replace first? Or just both and get it over with?

 

[570msp]

start with the one upstream, before the cat. and don't get a cheap one from autozone. get the $50-$60 one they offer. Trust me I've been done this road

edit: did you check your MAF? try cleaning it out? That may also be your issue if you're running a lean code

 

[therris]

I'll do that. Thanks.