check engine light

[benlauer40]

my check engine light keeps coming up with the same things I fix. O2 sensor. I have replaced them already and the light came back on, what do I need to do? I live in PA and we have emissons and I need the light to clear. At first the read out on what was wrong was, cat converter, O2 sensor, and EGR valve. The guy told me one thing could set this off for all 3. He said it is prolly the O2 sensors. So I replaced them, and now I am back a square one. ANy ideas?!

 

[Glacier991]

Ben thank you for not asking "I have a CEL, what's wrong". You have tried. Remember a CEL is really telling you that something is saying a "system" is not operating properly. O2 sensors are like warning stations. The station sensor may be wrong (it wasn't) or it may be telling you the truth. Yours was telling you the truth. That unhappytruth may have been caused by a number of things. To help we need to know the numeric code. Not what someone says the code means.,..... the CODE.... can you get that for us. LOTS of gearheads here happy to help but we need that data!

 

[TPLYNCH]

Get us the codes. Autozone or other parts shops will read them for free usually.

 

[r37ribution]

i have a '96 exploer xlt with a 4.0L OHV with this same problem. I'm getting a CEL light with 3 codes: "bank 1, sensor 1 heating circuit" "bank 1, sensor 2 heating circuit" "bank 2 sensor 1, heating circuit."

This happened about a week after changed my leeking stock muffler to a flowmaster delta 40 series, all 3 codes came up at the exact same time. So I replaced all 3 O2 sensors (which it was about time to do anyways) and unfortunately all 3 codes came back up within 30 seconds after the 1st start after i clearing with a computer.

on a side note: i use to have a pretty serious EGR issue in which i had to replace the EGR valve, EGR sensor, and snake out the EGR pipe coming off the exhaust mani with a bottle cleaner. the symptoms were a VERY rough idle. This issue seems to have returned, about every 10-15 starts when the engine is NOT cold the explorer runs very rough. I just rev to 3 grand a few times and it goes away.

benlauer40: did you recently change or do any mods to your exhaust?

I have 188,500 miles on my X

 

[BuffaloXplorer]

on a side note: i use to have a pretty serious EGR issue in which i had to replace the EGR valve, EGR sensor, and snake out the EGR pipe coming off the exhaust mani with a bottle cleaner. the symptoms were a VERY rough idle. This issue seems to have returned, about every 10-15 starts when the engine is NOT cold the explorer runs very rough. I just rev to 3 grand a few times and it goes away.

r37 - do you remember what EGR-related code you had? I've got a similar problem and replaced all 3 components and my code will NOT go away...

 

[Glacier991]

all 3 heaters going bad at once? not likely. You probably interrupted a wire is my guess. The heater has a 12V feed and in some cases a separate ground wire... The heaters come on when the vehicle is started to speed up heating up time for closed loop operation. You will be ok to drive without the heaters operable, you will just stay in open loop longer. Check your wiring to see if something didn't get damaged on your undercar work.

 

[r37ribution]

r37 - do you remember what EGR-related code you had? I've got a similar problem and replaced all 3 components and my code will NOT go away...

I dont remember the code number but i do remember the code description...something to the effect of "EGR sensor malfunction"

so i replaced the EGR sensor and 2 days later the code came back, so i replaced the EGR sensor again at Autozone under warranty.
the code came back again!
i knew it had to be with some other component of the EGR system. so I took a look into the EGR sensor's tubes and they were FULL of carbon, so i changed the 2 rubber tubes and replaced the EGR sensor again and replaced the EGR valve (which was also completely caked with carbon). I talked to a buddy before doing all this and he said get a baby bottle cleaner and snake out the exhaust line coming from the exhaust manifold or the carbon will just screw up your new EGR valve again. the baby bottle snake i had was way too big so i had to do some trimming off the plastic hairs so it would fit but it took a LOT of carbon out of the metal tube.

the code hasn't came back since but im gettin a rough idle again so i think i need to do some more cleaning...then again i used an Autozone EGR valve soooo i dunno!

all 3 heaters going bad at once? not likely. You probably interrupted a wire is my guess. The heater has a 12V feed and in some cases a separate ground wire... The heaters come on when the vehicle is started to speed up heating up time for closed loop operation. You will be ok to drive without the heaters operable, you will just stay in open loop longer. Check your wiring to see if something didn't get damaged on your undercar work.

So all 3 heater circuits are all on a series circuit? that doesnt make sense cuz how could the computer tell which heater circuit has gone bad? you dont think that adding a flowmaster (which we all know draws a lot of heat from the motor) could have caused the exhaust to run cooler on the stock pipes and make the computer think the heating elements arent working right? the heating circuit does in face heat the O2s its not a temp sensor right? i didnt think it was a temp sensor but someone mentioned that he thought it might be and that would make sense cuz after adding the flowmaster the exhaust would run a lil cooler

if the heating element doesnt work right does the CPU run off default F/A mixtures? cuz ever since i got this light im running 11.5MPG!!!!! 220 miles TOPS on a 19.1 gal tank! :fire:

 

[benlauer40]

r37ribbion: yes I did put on a new gibson exhaust. I went to auto zone today, now it reads that I have a bad EGR valve. It idles very rough like everyone has mentioned. Thank you all for your help.

 

[benlauer40]

r37ribution: yes I did put on a new gibson exhaust(got it for $10!) I went to auto zone today, now it reads that I have a bad EGR valve. It idles very rough like everyone has mentioned. Thank you all for your help.

 

[r37ribution]

wait people i still have a problem lol dont leave me!

Glacier991: ill check the wires like you said...

there is a grey, black, and white wire on the bosch O2's do you have any idea which is +12V? and if there is a ground or does it ground thru the exhaust?

 

[BuffaloXplorer]

r37ribution: yes I did put on a new gibson exhaust(got it for $10!) I went to auto zone today, now it reads that I have a bad EGR valve. It idles very rough like everyone has mentioned. Thank you all for your help.

Not even gonna ask how u got a Gibson for $10 - but anyway, telling us what the guy at autozone says means nothing - you gotta get us the code (i.e.p0401, p0402, etc.).

EGR related faults MOST of the time come from the DPFE sensor and NOT the EGR Valve itself. I'm one of the few that swapping the DPFE didn't work for. I've also swapped the EVR and Valve and still have the code (mine is P0402 - egr flow excessive).

R37 - if you don't have a Haynes manual, get one - i believe it has an electrical test for just about every component that you'd need one for.

 

[r37ribution]

DPFE sensor? where is that...are you referring to the EGR position sensor screwed on the side of the intake? I have an EGR issue as well, extremely rough idle only right after a warm start every 10-15 starts, no EGR codes (only those for my O2 sensor issues). i use to have 2 EGR codes "EGR sensor malfunction" and "EGR flow excessive" which were resolved by doing the maintenance i stated above.

 

[BuffaloXplorer]

Yeah, the DPFE is the EGR Valve Position Sensor screwed to the side of the intake.

My "EGR Flow Excessive" code has gone away for a few days but i expect it back soon.

To clean out the manifold pipe, did you remove it completely to do so? I had a b!tch of a time getting the EGR off the pipe but it finally did come off, and i can only imagine how hard it'd be getting the pipe off the manifold. Anyway, if i ever get ambitious, i may try that.

However, as i do not expect that a dirty manifold pipe is a significant contributor to my 10 +/- MPG, it's not a big deal to me.

 

[r37ribution]

Yeah, the DPFE is the EGR Valve Position Sensor screwed to the side of the intake.

My "EGR Flow Excessive" code has gone away for a few days but i expect it back soon.

I'm not getting a code, just a VERY rough idle right after starting but only occasionaly and it just happeneds after the engine is warm...reving the motor up to 2000-3000rpms a few times restores normal idle

To clean out the manifold pipe, did you remove it completely to do so? I had a b!tch of a time getting the EGR off the pipe but it finally did come off, and i can only imagine how hard it'd be getting the pipe off the manifold. Anyway, if i ever get ambitious, i may try that.

However, as i do not expect that a dirty manifold pipe is a significant contributor to my 10 +/- MPG, it's not a big deal to me.

I used a 27mm wrench to pull off the EGR valve and it came off will a lil force, i then used a baby bottle cleaner (i had to trim the bristles a little bit to make it fit) to snake out the EGR valve tube coming off the exhaust mani...the hard part was finding the 27mm wrench!

oh and i have the 4.0 OHV motor too in my '96 when i first got it at 154,000 miles i was getting 300+ on a 19.1 gal tank. now i have 189,5XX and im getting 220 miles on a 19.1 gal which is 11.5mpg and thats REDICULUS! the only thing i can think that is causing this is the issues with the O2 sensors...im tired of spending this much money on gas!

 

[explorer4x493]

shoot, mine was on so long that it burnt out.....I LIKE IT!!

 

[benlauer40]

I have replaced the EGR valve positon sensor, CEL went out for about 25 miles, then once got above 55 mph it kicked back on saying EGR insufficent. I have cleaned out the manifold and there was a little bit of carbon, not much, so I am now going to replace the EGR itself. If the codes come back on then what do I have to do? Also, once the light came back on it also tripped o2 sensor slow to respond, is that affiliated witht he EGR? thanks!

 

[r37ribution]

I have replaced the EGR valve positon sensor, CEL went out for about 25 miles, then once got above 55 mph it kicked back on saying EGR insufficent. I have cleaned out the manifold and there was a little bit of carbon, not much, so I am now going to replace the EGR itself. If the codes come back on then what do I have to do?...

If the light comes back on...(and this is a 4.0 OHV)
You can try replacing the rubber vaccum tubes that connect the position sensor to the EGR valve; you may consider doing this when you replace the EGR valve as well to prevent contaminating your new parts. Don't forget to snake out the metal tube coming off the manifold to the EGR valve if you haven't already done so.

...Also, once the light came back on it also tripped o2 sensor slow to respond, is that affiliated witht he EGR? thanks!

I have heard from a Ford tech that a false O2 slow to respond code may be tripped as a result of the failing EGR components.

 

[Kingkobra]

Yeah, the DPFE is the EGR Valve Position Sensor screwed to the side of the intake.

The DPFE is NOT the egr position sensor... It's the Differential Pressure Feedback EGR sensor........ It doesn't measure anything except pressure, not position.....

 

[r37ribution]

ok so where is it located? and could it get contaminated with carbon like the EGR valve and the EGR position sensor?

If it can get contaminated could this cause an intermittent rough idle?

 

[gss]

The DPFE is just below the IAC on the drivers side of the vehicle. You might also try cleaning the MAF sensor. If you do a search and look at those posts for both MAF and DPFE you will find several pictures.