OK Guys I'm Back....and with another issue...P0420

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JennsLincolnLS

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OK so here goes,
My last post on here I was going to replace all 4 O2 Sensors and see if it cleared the sensor code, which it did. BUT, now it is flashing a 0420 code and I think I may have clogged my cat it says catalyst system bank 2 low efficiency. What do I do if I have a clogged Cat is this something I can fix myself or is this beyond the scope of self fixing....do I have to trust a mechanic with my beloved car....I usually have more work when they are done too!!
Jenn
 
By flashing do you mean the check engine light is flashing and the code is 420 or is the check engine light in steady and the code is 420?

I have had an intermittent 420 code for the last three to four years. Whenever I drive long distances on the highway (over 150 miles) the light comes on. If I drive long distances of steady stop and go traffic (~150 miles) the light goes out. Luckily I've always had a period of time in July (annual State inspection) where the light has been out and I've gotten through inspection. This all started when a I had a miss fire and drove a couple of days waiting for the coils to arrive.

This year the light has been on steady since April. I was considering changing the O2 sensor but the light went off this weekend, after driving through Brooklyn. So I'm not using the car again until I get it through inspection in early July. Then I'll be done for another year.

You could fool the computer by installing two spark plug non-foulers on the the downstream O2 sensors (just to confirm the problem since tampering is illegal). Do a google search to learn this diagnostic technique.

2000 V6 Manual Transmission 138,000 miles - original O2s and Original cats
 
Sorry the check engine light is not actually flashing it is on and steady and the code reads P0420 when run on a diagnostic machine at shuck's....
Thanks All!!
 
JennsLincolnLS said:
What do I do if I have a clogged Cat is this something I can fix myself or is this beyond the scope of self fixing...
Click to expand...

well its a simple ideal, but the work itself is a pain in the @ss, especially on jack stands


its as simple as removing the old cats and reinstalling the new cats, the hard part is getting the old one off, you will have to use a couple of long socket extensions and a wobble bit or two, two bolts for each header flange, then there is two bolts behind the 3rd cat (one for each pipe) to separate the whole cat assembly from the rear half of the exhaust system, now the tricky part is getting the cat section apart from the rear section as when i did mine they where rusted together and had to be cut apart (which meant it needed a trip to a shop for welding)


pragmatic said:
You could fool the computer by installing two spark plug non-foulers on the the downstream O2 sensors (just to confirm the problem since tampering is illegal)
Click to expand...

this was my plan as instead of replacing the clogged cats, i just hollowed them out so it could be driven while i round up the parts for a custom setup of aftermarket cats instead of the oem parts, the problem i ran into is that there is no room for the non foulers as with them in the trans is in the way of the sensor
 
Your cats are toast.

You should be able to pass a tailpipe 'sniff' test if you have a clean air filter, good coils, wires, plugs and fresh oil. Ain't closed loop fuel injection wonderful.

Sadly, the engine computer is still going to rat you out.

This beast has four O2 sensors. One function the computer is going to test is to compare the signals from the front and rear O2 sensors on each side. The signals will be the same if you don't have cats and you get the 'Service Engine Soon' light (P0420, P0430).

An MIL Eliminator will plug in line with the rear O2 sensors and fool the computer with a reduced signal. The front O2 sensors will still be part of the emissions system.

Hope this helps.
 
dtpoirot said:
Your cats are toast.
Click to expand...

Not necessarily. I've had this code off and on for four years. As I've said heavy stop and go driving (for ~150 miles) causes the car to self clear the code (on my car at least).

The algorithm looks for how fast the upstream O2 is switching (and how far its swinging) from lean to rich and if the downstream O2 is swinging less once warmed up. This is why the non-fouler will fool the ECM (it lessens the swings of the down stream O2 sensor).

Knowing how the code is generated, if I was only going to change one thing (and I don't want to cheat with the non-fouler), I'd change the upstream O2 sensor. May not work but certainly cheaper and easier than the cats.
 
Is this a code that could have popped up if I messed up and installed front o2 sensors on the rear and rear o2 sensors on the front? two different part numbers but I messed up and didn't know which was which so a friend of mine helped me guess...bad idea? I know I can take it to midas and have it hooked up to a diagnostic machine for about $76 but for them to do the cats it will cost $825 parts and labor...ugh one more thing gone wrong with my beast!!!
Jenn
 
<pragmatic> ...and your cats haven't been the issue for four years? The (possibly toasted) cats may be operating in a sub-optimal manner or the signals from the two O2 sensors wouldn't be the same... Right?

<JennsLincolnLS> Not sure if there is any difference between the front and rear O2's. BOSCH part numbers 15716, 15717 and 15718 are all listed as direct fit. The only difference is the length of the cable.

The "non-fouler" is a bushing with a spark-plug thread. The idea is to back the O2 sensor out of the exhaust stream, providing less of a signal.

The MIL eliminator plugs into the wireing harness inline and reduces and shifts the rear O2 signal electrically.

A strong, vigerous signal from a fresh upstream O2 and a tired signal from a nasty, old downstream O2 sensor will have the same effect.

Which part is cheating? If you get the 0420/0430, how do you fix it? Replace the cats or reduce the signal from the rear O2's...
 
JennsLincolnLS said:
Is this a code that could have popped up if I messed up and installed front o2 sensors on the rear and rear o2 sensors on the front? two different part numbers but I messed up and didn't know which was which so a friend of mine helped me guess...bad idea?
Jenn
Click to expand...
it is very easy to tell which sensors go into which location, the front sensor (pre cat) has a blue connection and the rear sensors have a green connector, the car side connectors at the trans are also green, im not sure if the blue sensor will even plug into the green connector, but it should be very easy to see if there is a blue sensor plugged into a green harness
 
dtpoirot said:
<pragmatic> ...and your cats haven't been the issue for four years? The (possibly toasted) cats may be operating in a sub-optimal manner or the signals from the two O2 sensors wouldn't be the same... Right?
Click to expand...

Sub-optimal maybe but not toast.

Depends where FoMoCo engineers decided to light the light. If they chose 95% cat efficiency they will annoy the customer with lots of repair work. Too much below 80% and they run out of room on their deterioration factors and annoy EPA.

The fact that under stop and go driving the code clears, means (to me at least) that the cats are working pretty well, just no up to the line the engineers drew in the sand.

This link is a chemical sales site, but good info on the P0420 code is provided:

http://www.etechchemicals.com/pdf/P0420CatEfficiency-Bank1Explained.pdf
 
1LoudLS said:
it is very easy to tell which sensors go into which location, the front sensor (pre cat) has a blue connection and the rear sensors have a green connector, the car side connectors at the trans are also green, im not sure if the blue sensor will even plug into the green connector, but it should be very easy to see if there is a blue sensor plugged into a green harness
Click to expand...

The bosch after market o2 sensors both have black wires and I forgot which part number was which, the only difference in appearance is one has a shorter wire than the other....That is why I'm not sure I got them in the correct place....I'm gonna just have to take it to a shop and have them give me my options....wish me luck...I hate trusting my baby to anyone but me after the darn ford dealership didn't fix the issue I had it in for and it cost me $800...
 
Are you sure that you don't have a bad coil? That will mess up a cat in a hurry. Was it running ok when the code came back?
 
The thing that bothers me... Isn't the cat damage irreversible even if the coils are swapped for good ones? I have a damn good feeling my cats are just clogged from the marginal coils pripr to my repairs.
 
diskfunktional said:
The thing that bothers me... Isn't the cat damage irreversible even if the coils are swapped for good ones? I have a damn good feeling my cats are just clogged from the marginal coils pripr to my repairs.
Click to expand...

I'm in the same boat! My passenger side coils were bad from neglect and time so when I did the spark plugs I did the coils but I think that I messed up my cats when I was running with a backfire....is that something that happens?
 
^^Happened to me. I Bought my car off my brother-in-law.. my sister was driving it around with a bad coil. Replaced the coil when I bought the car, and one of the cats ended up going bad. The dealership said that they've seen it a few times, when people neglect the check engine light..
 
Ok I'm back again....with a related question....I have determined that I am going to replace my cats....can I buy the ones off of rock auto that are direct fit and do it my self (or with the help of my mechanic friend) or am I better off taking it in somewhere and having someone else do it?? All advice as always is much apreciated!!
Jenn
 
it is not too difficult to remove and replace the cats as long as its not rusted and seized together.

basically it should be a 30 minute job, all you have to do is unplug all four sensors, loosen the two bolts for each header flange, and then loosen the two clamp bolts that hold the cat system to the rest of the exhaust system, and it should drop right out. then remove the old o2 sensors from the old cat piping and place them in the new cat piping (if you have a lot of miles on you car or you have been driving with a miss for awhile, you might as well just replace all the senors now while your at it) and then bolt the system back together.


now for why there where a lot of should's in there. first off, the header bolts, soaking in PB Blaster a few time, a couple of days before you try the job is a great ideal because they will be hard as hell to get off, and because of their location they are a real pain to get to (i had to use two long extensions and a couple of wobble bits to get to them)

and the rear two bolts where real easy to get to, but even after they were completely loose, the two halves of the exhaust were fused together and no amount of heating, beating, and banging could break them apart. so out came the sawsall and the pipes had to be cut, which then had to be taken to be welded back together.

a simple 30 min job, turned in to a weekend of four hours of wrench time, 30 mins of the loudest driving ever, and 45 min of shop time for welding.
 
Well Thank you SOO MUCH!! Because I have someone that can help me do the work and knows how to and has acess to a welder just incase we need to cut the pipes...I think I will do it when I have a couple days free anyways just incase it ends up taking longer than anticipated....I'm also gonna have to replace a COP because I "think" the clogged cats caused one of my cop's to burn out...I've got a miss again...ugh...hopefully once I get this all done I can do my clockspring and be done with it...as long as I keep up on the regular maitenece I'm hoping all the big bad stuff is done breaking!!! :)
Jenn
 
OMG you have got to be kidding me!! Did I believe idiots when they told me I had to spend $70 on 10 lug nuts for my 01 LS!! Are you kidding?! I had to do my front brake pads and rotors and my lug nuts were so stripped i had to buy new ones but they were dealer only and $6.53 a peice!! WOW!!! SO It took me all morning to get the darn wheel off only to find out when I finally got the brake pads off I needed new rotors!!! WOW...does every job I try to do have to cost more money and be bigger than it should be?? Now I'm really worried about doing the cats myself...but they are in the mail and I am about to try this!!!
 
yea, its definitely no joke about the cost of maintenance on this car, thats for sure.

however the whole lug nut fiasco shouldn't be a part that you should have to replace too often, yet its something that most people will have to deal with.
 
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