Hi all,

I have a 96 Explorer that I recently had the engine profesionally cleaned.(big mistake!) When I picked it up from the cleaning it ran rough for a couple of miles and eventually smoothed out. The real problem is, the check engine light came on and has been coming on and off for about 3 weeks now. I can't correlate the timing with anything specific. I have had my tustworthy mechanic check it out a couple times but he does not get any codes from the computer. His hunch is something got wet during the cleaning but he is puzzled as to what it is, since he does not get any codes. The engine seems to run fine but this light is "driving" me crazy. Any suggestions would be appreciated. Thanks.
Kevin:-)

 

Try going to a mechanic that knows how to read the codes. If your Check Engine Light is on, it is on because a code has been set. Now if the light is going on and off and he is checking it when the light is off, there won't be any codes. Make sure he checks the codes with an OBD-II scanner while the CEL is on. Try stopping by Autozone the next time it comes on. Many people have reported Autozone reading the codes for you for free.

 

Thanks for the reply. The problem is his OBD-11 scanner is not getting any codes at all, even when the CEL light is on. One time he checked it and he could not even comunicate between the scanner and the computer. He had to reset it by pulling a plug(not sure of the details). Light was out for 2 days then came back on. Is any of this possible? Could there be an electircal problem? I've been going to this mechanic for 10 years and have never had a problem. I'm pretty frustrated now and don't even like driving the vehicle because the light is always on now. I can't ignore it anymore.

 

I would try a different OBD-II scanner when the light is on. It is possible that the problem is an O2 sensor. You can try spending the $100 to replace them, but if that isn't your problem then it will be money wasted. What brand and model scanner does your mechanic have? Is it Ford Enhanced OBD-II equipped? Does it only read in Generic mode? It is possible that his scanner isn't capable of reading your Explorer's codes. If that is the case, then your only choice is to find one that is.

 

Any other suggestions?

 

Some DTC are manufacturer specific & cant be accessed expect with the Ford NGS ( Next Generation Star Tester )

 

I took it to Autozone for a scan and they got CODE P0420 which is "Catalyst system efficency below threshold (Bank 1)" Can anyone please shed some light on this and give some idea as to what the problem is. Thanks.

 

Here are some things that will cause PO420 : Engine misfiring , If the spark plugs are in need of replacing , replace them with the proper ones , Dont use Bosch Platinums . Proper coolant level & quality , damaged wiring to the rear O2 Sensor , Fuel pressure too high , any damage to the exhaust system . Has the engine misfired , any trouble starting it , black smoke etc ? Were any other codes present ?

 

Here are some things that will cause PO420 : Engine misfiring , If the spark plugs are in need of replacing , replace them with the proper ones , Dont use Bosch Platinums . Proper coolant level & quality , damaged wiring to the rear O2 Sensor , Fuel pressure too high , any damage to the exhaust system . Has the engine misfired , any trouble starting it , black smoke etc ? Were any other codes present ?
FTE Moderator



Thanks for responding Paul,
The vehicle starts and runs fine and no black smoke. And no other codes present. The only thing I've noticed is some water dripping from the tail pipe at start up, then it goes away. No smoke of any color present.

Just before the CEL problem it had a complete tuneup, plugs, wires, pcv, fuel/air filter etc. Could a new plug be bad or gapped incorrectly? How can I tell if the fuel pressure is correct? In the morning I will check the coolant and exhaust for any obvious problems. Were are the two 02 sensors located? Sorry so many questions.

 

If the CEL came on shortly after the tune up was done then Id suspect there in lies the problem . Like I said , A continued misfire can cause the PO420 code to be set . If its doesnt have the proper Motorcraft plugs thats a good place to begin . Start there with your diagnosis .

 

 

You won't believe this but I have had the same problem w/mine. At first the code was saying "misfiring" and I have already replaced the spark plugs w/no success...THe light came back on and is now giving a different code - saying it has something to do with emissions...I have now been told to replace the cadilitic converter (sp?) and have an appt. to do this in the morning. I have no idea if it will work but I definately know what you mean about being frustrated and not wanting to drive it anymore....I am really hoping that this tomorrow will fix the problem...Mine also runs loudly as if I have a glass pack installed but I don't. Any help or suggestions for me would be appreciated!!!
I love this truck and if I could get this fixed once and for all would really enjoy it and have peace of mind! I hope to hear back from someone who can help soon!!!
2/2/05 6:20pm

 

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