shellhead

Greetings:

I have a 1998 v6 24 valve contour that appears to drive fine. The engine light is always on. Ihave had several repairs to correct this condition including a tune-up that incljded a new fuel relay and replacement of the front oxygen sensor.

My mechanic says its a hard code...I don't have the number here now, but will get it later...I am loath to just replace one part afte the other to try and correct the problem...partticularly when eacha repair doesn't seem to keep the code light off for more than a few days.

What can I say to the mechanic to have them diagnosis the true reason(s) that the engine light keeps coming on?

Does anyone have suggestions?

Thanks for any help

bye for now

Shellhead

LunaticSVT

first you need to find out what codes you are throwing. Most dealerships will run to see what codes you are running free of charge. Just tell them that you have a check engine light and you need to know what codes are being thrown. Most dealerships are good and will just do that for ya.

Once you have that then a proper diagnostics can be determined from that.

Is there anything that you have noticed about the car itself? Does it hestitate? Does it smell like you are running rich? any knocking? Any loss of power? All that will help in determining what the problem may be.

shellhead

Thank you for your reply. The car seems to run fine, there is no noticeable performance problem. I am concerned an error code that seems to point to an oxygen sensor, may be really a "upstream problem", like fuel pump weakeness, clogged filter/injector, etc.

I will pursue the dealer inguiry and see if they are certain they can pinpoint the real failure---and not just find myself throwning parts at the car.

I will post back later with the actual coce number invovled.

bye

LunaticSVT

have you checked your cats? I had a clogged cat that was causing me issues. Was getting codes for running rich on the left bank. Ended up being a clogged cat. Now this is not something that may be affecting you, but it is something to look at too.

shellhead

Thanks for that tip....I will find out if the code could be an "upstream" or downstream problem.........I will post back as I progress with this problem....of course my real concern is just getting it fixed without having to throw parts at the engine!

bye

LunaticSVT

aye that is understandable.

shellhead

Greetings Again:

So the error coce is a P0420...I understand this can be a bank 1 o2 sensor or an ECt sensor and also a catalytic converter problem.

How can I assist the mechanic to direct their efforts to pinpoint the real problem? They replaced on 02 sensor they said was "bad"----I guess I would like to know what "bad" means...rich/lean, etc.

Since their new 02 sensor still leaves on the CEL I guess it is still p0420...I will find out for sure when they rescan.

I susspect they should also check fuel pressure.

Does anyone have a most likely direction to suggest?

I think it is fair that if a mechanic says "here is the problem"...they replace the failed part...and the problem still exists...then their repair is wrong and any future repair suggested should be warrantied by them... that if their next repair does not fix the problem, they should eat that repair cost---sort of having confidence about their own judgement with their own wallet. Why should I pay for repairs that don't repair? Seems fair to me.

I wonder if the brand of 02 sensor is crictical to a repair?


bye

LunaticSVT

p0402 is Catalyst System Efficiency Below Threshold (Bank 1)

I just re-read what you first typed. Did the dealership not replace the rear o2? on 96 and new they should have both a front and rear o2. If you are still getting the above error code and the rear was never replaced then that could be your issue. o2's are pretty straight forward to replace and you can do it with jackstands a good set of wrenches. Only thing you would need is to have the dealer flash the code out and most will do it when you show them that you replaced the o2's

If you can do it yourself I would suggest going that route as the first step. If it continues to be an issue with the CEL coming on and the same DTC look at a clogged cat or even an old cat. How many miles do you have?

and the brand of o2 will not matter. The only thing you should worry about is that it is the right type, but if they look up the part it will list the correct replacements for non Ford or motorcraft versions.

shellhead

Greetings:

Thanks for your informative reply, I will follow up with the mechanic and post back any improvements

bye