So the title speaks for itself, I have a 99 SVT its throwing the P0420 Bank 1 Something about emissions anyways the car seems to stumble slightly under light acceleration more noticibly when the car is cold and usually in lower gears, but anyways What are the possible causes?
-
Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.
You can register to join the community.
99 Svt P0420
- Thread starter mattp182
- Start date
Big Jim
Hard-core CEG'er
P0420 is a cat effeciency code. In theory it means that one of your precats is not effecient.
I say in theory because on our cars it is often a false code.
This code does nothing to explain those other symptoms.
There is a world of information on this from past threads.
I say in theory because on our cars it is often a false code.
This code does nothing to explain those other symptoms.
There is a world of information on this from past threads.
projectSHO89
Hard-core CEG'er
Plugs/wires for the misfire/stumble.
SEARCH keyword "P0420"
SEARCH keyword "P0420"
A vacuum leak could explain stumbling and also the eventual P0420. Check for leaky hoses or gaskets. Spray with carb cleaner. If idle changes, you found the leak.
Woogieman
CEG'er
My buddies 99 SVT is having a very similar problem. We have replaced the fuel filter, & plugs. We've also replaced the wires, but the first set we used were defective & the second set (Borg Warners) made the car missfire while idling, & drive like it was running on 4 cylinders (missing on 2). We put the old wires on and the idle is okay but the original problems still exist. He also has the p0420 code. Any other help would be great. My friend is so frustrated he wants to take his car to a Dealership now.
-Aaron
-Aaron
After finding the leak, erase the P0420 code and if it appears again, time for mileliminators. Good luck.
rocketmanrw
CEG'er
anybody check their 02 sensors?? thats what it was on mine
Just an FYI, there was a TSB that called for the ECM to be reprogrammed due to he threshold was too narrow for this type of fault, hence logging the code.
Make: FORD Model: CONTOUR Year: 1999 Service Bulletin Number: 04104 NHTSA Item Number: 10008993 Summary Description: MALFUNCTION INDICATOR LAMP ILLUMINATED WITH DIAGNOSTIC TROUBLE CODE P0420 AND/OR P0430/ 2.5L ENGINE ONLY. *TT
Make: FORD Model: CONTOUR Year: 1999 Service Bulletin Number: 04104 NHTSA Item Number: 10008993 Summary Description: MALFUNCTION INDICATOR LAMP ILLUMINATED WITH DIAGNOSTIC TROUBLE CODE P0420 AND/OR P0430/ 2.5L ENGINE ONLY. *TT
Even with the reprogramming the code can come back on after a period of time.
Had the same issue with my daughter's SE, dealership said the pre cats were bad, strung her along for a bit by telling her that they had been ordered and then refused to replace them. They reprogrammed the ECU and within a week the code was back, they then told her it was the DPFE. They replaced it and still the code came back. :crazy:
I'm not saying that once reprogrammed that the CEL will come back on in a week, it's normally a much longer period than we experience. Still, it can come back after the reprogram.
I was getting sick of hearing that the CEL was on so I bought her headers and MIL eliminators, no more CEL.
I would do as Tony suggested: spray the carb cleaner to check for leaks first and see if you can find one.
Had the same issue with my daughter's SE, dealership said the pre cats were bad, strung her along for a bit by telling her that they had been ordered and then refused to replace them. They reprogrammed the ECU and within a week the code was back, they then told her it was the DPFE. They replaced it and still the code came back. :crazy:
I'm not saying that once reprogrammed that the CEL will come back on in a week, it's normally a much longer period than we experience. Still, it can come back after the reprogram.
I was getting sick of hearing that the CEL was on so I bought her headers and MIL eliminators, no more CEL.
I would do as Tony suggested: spray the carb cleaner to check for leaks first and see if you can find one.
I just had Both p0430 and p0420 on the mystique and p0430 on the SVT. I fixed the problem with just replacing upper o2 sensors. The SVT's sensors had 90k on them and the Mystiques had about 50k after replacing them once already to get rid of the code. The codes have not reappeared for over 2 months on either car. This has now worked twice on the Mystique for 50k miles.
Woogieman
CEG'er
I understand the code issue, I just wondered if anyone had ever experienced a car running worse with new wires. Could this mean that something else is causing the P0420 code? It was missing very bad, & an awful smell was coming from the exhaust. I'm assuming from the fuel not burning properly? I would expect a vacuum leak to be the same regardless of new or old wires.
Please keep the ideas coming. I would love to solve this problem for my friend.
-Aaron
Please keep the ideas coming. I would love to solve this problem for my friend.
-Aaron
Gerry_M
New CEG'er
The 0420 code certainly is "annoying".
FWIW, mine started giving that code at 79,000 miles. Since the car was OVER 8 years old the dealer wanted $2,700 to replace the pre-cats. I told him to go u-know-where. (He still charged me $140 to 'diagnose' the problem - I already knew it was the precats coz, even back then, I had my own code-scanner.)
I 'flushed' the cats by introducing a can or two of Berryman's B12 *directly* into the UIM - via a vacuum line - together with a can of Seafoam or B12 or 'Catalytic Converter Cleaner' in the (full) fuel tank as I drove.
Later on, for the 90K service, they (i.e. the dealer) re-programmed the ECM so as to have the 'wider margin for cat efficiency' and it hasn't come back since.
FWIW, before you go start replacing things, put a can of Berryman's B12 or Seafoam into the gas tank and go drive the car (having first cleared the CEL). Put another can into each of the next two full tanks of gas so that you end up running *three* "treated" tanks of gas thru' your engine.
Chances are the CEL for 0420 will NOT come back again. If it does then MIL eliminators are your next best bet.
Gerry
FWIW, mine started giving that code at 79,000 miles. Since the car was OVER 8 years old the dealer wanted $2,700 to replace the pre-cats. I told him to go u-know-where. (He still charged me $140 to 'diagnose' the problem - I already knew it was the precats coz, even back then, I had my own code-scanner.)
I 'flushed' the cats by introducing a can or two of Berryman's B12 *directly* into the UIM - via a vacuum line - together with a can of Seafoam or B12 or 'Catalytic Converter Cleaner' in the (full) fuel tank as I drove.
Later on, for the 90K service, they (i.e. the dealer) re-programmed the ECM so as to have the 'wider margin for cat efficiency' and it hasn't come back since.
FWIW, before you go start replacing things, put a can of Berryman's B12 or Seafoam into the gas tank and go drive the car (having first cleared the CEL). Put another can into each of the next two full tanks of gas so that you end up running *three* "treated" tanks of gas thru' your engine.
Chances are the CEL for 0420 will NOT come back again. If it does then MIL eliminators are your next best bet.
Gerry