Contour Enthusiasts Group Archives Forums General Troubleshooting P0401, P0420 Codes

'96, 2.5L, 106,000, no mods... I've had this insufficient egr flow code for about a year and just a couple of days ago the beast started to "buck" (fluctuating rpms, felt like it was down shifting, hard bangs, etc...)

Then pulled the 0420 code which is an oxygen sensor. Drivers side, upstream.

1. Could the egr code contributed to the oxygen sensor fouling.

2. Can the sensor be changed without putting the car on ramps, or a lift?

FordBum wrote:

Then pulled the 0420 code which is an oxygen sensor. Drivers side, upstream.

  P0420 means ?Catalyst System Efficiency Below Threshold (Bank 1)?.  Ostensibly, this means your bank 1 precat has gone bad and needs to be replaced.  It's possible that this is really an O₂ sensor problem, as there is an O₂ sensor before and after each precat, used to monitor their condition.  I've been told that EGR problems can cause wonky O₂ sensor readings, and it seems to me that this, in turn, could cause the PCM to think the cat's gone bad.  As someone else is going to post some time after this posting, I suggest that you fix your EGR problem first.  BTW, I do not agree with the advice that someone else is going to offer, of cleaning your EGR valve.  I tried that once, and it only solved the problem for a short time.  Given the amount of work involved in removing and replacing the EGR valve, it only really makes sense to remove a questionable valve if you have a new one to install in its place.

  Oh, and one other thing.  It might not be the actual valve at all.  I understand that the Duratec is subject to having the EGR passages become blocked with carbon deposits.  Perhaps someone will post here with instructions for checking and cleaning these passages.

1. EGR problems could cause future O2 sensor (or other) fault codes. Your 0401 code (Insufficient EGR Flow) seems to indicate clogged up EGR passages, a vacuum leak to EGR valve, or some other problem.

2. Yes, all the sensorcs can be changed from either the top of the engine, (Upper sensors) or by jacking up the car so you can slide underneath to get a wrench on lower sensors on the exhaust/y-pipe. (I think the 0420 code would indicate problems with the pre-cat or the lower sensor rather than the upper sensor)

I would try to clear up the EGR problem before swapping out O2 sensors. A good EGR cleaning can do wonders. Also check for cracked or disconnected hoses.

Been chasing this egr problem for a while now, replaced cracked hose, minor clean job (pulled away from intake and sprayed with cleaner), all to no avail.

I'll do a search for tips on taking that thing off. I tried to get the EGR off once but couldn't get enough leverage to break the nut loose. (or I could just be weak.)

Thanks

Okay, I went ahead and pulled the upper intake off and found my P0401 problem, I think. The little channel where the egr gas goes back into the manifold was completely gunked up with carbon deposits. I went ahead and had the upper intake dunked to clean it all out. Broke one of the vacuum lines going into the intake though.

Also, going to go ahead and replace the egr valve anyway.

Should I go ahead and go further and take the lower intake off? It's got some pretty bad carbon buildup on it also.

Thanks

If you have the time and the gaskets to pull the lower and clean it up, go for it! While your cleaning the secondary butterfies, file off the extra screw threads. Better yet replace the screws with countersunk screws and then file off any extra threads.

Got a part question. I need to replace one of the two vacuum lines that come from the EVR (EGR vacuum regulator, I believe) and go into the intake manifold. Called a few places to no avail so I went to Ford and they couldn't figure out what I had so they printed out a picture of the exploded view of the fuel and air systems.

We finally figured what might be what I'm looking for but they said a cost of $25 bucks just for one piece of hard plastic vacuum tube.

1. Does any one have any experience with this part (part no., price etc...)

2. They couldn't tell me if the little piece that goes into the manifold that the tube snaps into come with it. Any help or do I just wait until the (guessed part) come in.

If its the hose next to the brake booster hose, it comes with the the connector for the manifold. (I melted one with my shop light ) In general, if the connectors are permanently fastened to the hose, the new hose will include the connector. (They don't want the techs waisting time with a $2 connector when they can just sell you a new one

If the hose is one of the skinny hard green plastic ones, you can repair a crack or break by coating the pieces with RTV silicone gasket stuff, and then coverig the crack/joint with a 2" section of aquarium type air hose.

How big (in diameter) is this EGR "channel" that you are talking about. I would like to clean it out by removing the throttle body, but I want to know what size pipe cleaner I will need.

Don't know the size of pipe cleaner, I just used a toothpick to get the clumps out. I went ahead and got a wild hair and took the UIM off. Had it dunked and it came out nice a clean.