Check Engine Light - What the #*&&!!

[madams557]

Okay, it is late and I've been on the road all day. I will caveat my question with the fact that I have pulled a search and I'm sure the problem is the O2 sensor, but I'm just too tired to remember how to determine the Problem Code.

Okay, it is a 95 FZJ80 with 190,988 miles. It was a mild day today in the mid 80s and I was on my way back to Fort Collins from Denver. I normally fill up with gas at Shell (only because of location to my work and home), but while in Denver I ended up filling up a full tank of gas at a Phillips 66 (I think).

Anyway, about ten minutes from the gas station, the check engine light came on. I pulled over, checked the oil and temperature - everything fine. My first impression was that this was a dummy light triggered by the fact that I went over 190K miles and it might be a 'special' maintanence interval. Believe it or not, my 1987 Nissan Sentra did this at 60K back in 1991 when I was in college. Anyway, I drove it for another 70 miles observing oil pressure and temp and listening carefully - nothing.

In the end, after a quick search of the IH8Mud collective mind, I bet it is a O2 Sensor. If it is, then I'll continue to drive it until I get time to have it replaced.

HOWEVER - if someone chimes in and tells me that I should be concerned and take it do the dealership the first chance I get, then I will.

So please, let me know if my suspicions are correct.

 

[robbie]

You do not have to go to a dealer unless you want, but you do need to have the codes pulled to see which of about 30 codes it might be. It might be a o2 sensor but which one, or the EGR code. Or you can clear the codes by pulling the EFI fuse in the fuse box next to the battery box. Pull it for a minute or more. Then start the truck and see if the CEL light is still on. If not drive it until the code comes back on. Some times you will trip a code for many reasons. Some DIY have a code reader and the FSM to tell them what is wrong. It really is not great to ingnore it until you know what the problem is. later robbie

 

[semlin]

welcome to the mud board and thanks for searching before posting. that light is not a maintenance interval.

the check engine light alerts you that something is amiss in your truck. A code is now stored in your vehicle's computer on board diagnostic (OBD) system. A 1995 vehicle has an early generation "OBD 2" system which requires a special scanner device to read the code.

At 190k it could be any number of things and an o2 sensor would be a blind guess even if you have reason to believe one is on the way out. Some of the problems can affect the operation of your vehicle or indicate conditions that can lead to other problems so the best thing to do is go find out what code it is.

I would have the code pulled immediately (especially if the light stayed on instead of flashing briefly) and then you can decide if it is something you can ignore. You need to take it to a shop that has an OBD2 scanning capacity. Toyota is one option. I believe autozone may be another. Either way the charge just to pull the code should be nominal. If they give you the code we can tell you what the fault indicates. If it is something you can ignore we will tell you.

 

[madams557]

Thanks Robbie. I'll work on running down the code tomorrow. I'm surprised you were at your computer today, wasn't Brendan Lal planning a trip up to the mountains today?

I wanted to go, but it seems my national guard duties have been clashing with the last couple of trips.

Thank you again, and I will work on narrowing this down in the morning.

 

[landtank]

How about a bad gas cap or maybe you forgot to put it back on!

 

[madams557]

Landtank, would you believe that thought crossed my mind. When I pulled over, I popped the hood and the gas door at the same time and checked the gas cap first. I turned it for a couple of clicks.

It could be the cap, but I'll follow up on the code to see what direction that sends me in.

 

[PHAEDRUS]

michael,
pull the efe fuse out for a few minutes and then replace it, start the truck and I have $5 that says it will stay out for a while.
or go to auto zone as suggested by others and see what it is.
Dave

 

[Rookie2]

I got $5 that says he won't find any efe fuse

Sorry fAvE, haven't fired one at you in a while... LOL


Rookie2

 

[madams557]

Hey guys, thanks for all of the input. Again it is time to have the front brakes done, so I have an appointment to have them replaced this Friday. While its there, the service guys are going to run the test to see what it is and let me know. I've asked for the code, so I will keep the board updated on what I find.

Hopefully I can get it all done on Friday, because I want to try and take a quick run up Crystal Mountain/Moody Trail (N. Colorado) this Sunday to help a friend scout out a possible hunting spot.

 

[robbie]

I was working on the SAAB for a trip we are going on, but some isssue came up and we are now taking the cruiser, pay the price in fuel for realiability. later robbie

 

[madams557]

Robbie,
The mileage has to be better with the 4.7 in there than the 4.5. And really, you won't get nearly as many heads to turn if you were taking the Saab.

 

[madams557]

UPDATE on Code Found

The dealership said that the code reported was P0401 - EGR Flow.

The mechanic said that he ran whatever test he is suppose to run and found no problems. He reset the computer and told me to see if it comes on again, that something might have tripped the computer but was an isolated problem.

So I was able to get the truck back in time to go wheeling up the mountains. It still running good, but it seemed to run a little hot yesterday - though the thermostate didn't show it. It might have been due to being stuck in traffic with 30 over wheelers on a steep grade when a 1988 Ford Bronco at the front of the line broke down.

I did have two spooky moments. While crossing a mud hole I banged my front diff really hard against a hidden rock (enough to pop the truck in the air). Then next was having a really small rock wedged in the bead lock on a front tire that started a slow air leak. No big deal to change the tire, but the nearest flat spot was down a rock laden trail.

But all ends well. Nice good scratch on the diff and a flat spare.

 

[Beowulf]

>> The dealership said that the code reported was P0401 - EGR Flow. <<

Michael,
There's volumes here on IH8MUD on this one. There is NO single fix and you can be comforted that it shall return. I cannot recall a single instance where someone got the P0401 and it went away on it's own. It may take several months and it is a 2-trip logic. If you are running "a little hot" at idle then the P0401 is unrelated. EGR doesn't kick in at low speeds or low RPM.

-B-

 

[landtank]

I'd be surprised if that code fixes itself

 

[Junk]

Michael,
May as well start preparing on the P0401 code. There's a FAQ for it up in the FAQ section. That code had me in the rubber room for a while.

All is fixed now though. So it won't hurt your truck to run with that code for awhile, but may as well start reading on it now.

 

[semlin]

My suggestion is to pop the plastic cap off the egr modulator (the small flying suacer thing nearest to the passenger side in the middle back of the engine) and see what the carbon filter looks like. This will take two seconds. If there is carbon I would fix the problem now. If there is no carbon in there then you can drive it for a while if you want.

Junk, I disagree that it won't necessarily hurt to run with that code on. It won't hurt the motor much other than maybe running a little lean, but it may greatly increase the cost of fixing the EGR system when you finally have to face the music.

If the cause is a busted EGR modulator, as it often is, he may be circulating exhaust gases through his vacuum system which will deteriorate and plug up all the vacuum hoses and metal piping and cause the hoses to deteriorate and the piping to corrode, plus block the throttle body ports. Some people also believe that the carbon in the gas is what causes the VSV to fail.

Doing this early in my case would have saved me having to replace a perfectly functional EGR valve because the nipple on the top had rusted up and plugged so I could not get a seal.

 

[Beowulf]

I agree with Semlin and the logic makes a lot of sense and follows what many of us have experienced.

-B-

 

[Rookie2]

Michael,
May as well start preparing on the P0401 code. There's a FAQ for it up in the FAQ section. That code had me in the rubber room for a while.

All is fixed now though. So it won't hurt your truck to run with that code for awhile, but may as well start reading on it now.

Junk,

Just curious, what finally curey your P0401?


Rookie2

 

[madams557]

AWH Great!!

So let me recap here.

When the mechanic did his check of potential EGR problems, it might be possible that he did not pop off the plastic cap of the EGR modular and see if there is carbon filter in there???

I will do that myself this week regardless.

SEMLIN - Help me out here. You suggested that I pop the cap off and look for carbon. Then you suggest that if I see carbon, I would fix the problem now.

- How do you suggest that I FIX the problem?? Buy a new EGR?

Also, you said that if I don't see carbon in there then I could drive it for a while if I wanted to.

- That comment doesn't give me a warm and fuzzy. Are you suggested that I need to fix this either way?? Yes, then please give me a glimpse of what is involved.


Tell me honestly, am I being faced with the Land Cruiser equivalent of triple-bypass surgery here?? I'm not off to the FAQ section.

 

[semlin]

umm, more like the Toyota equivalent of a flu, but the parts and labour will add up on you unless you do it yourself. mechanics will be tempted to throw new parts at it which only works if you replace everything at once..

The EGR system is designed to reduce emissions by recirculating exhaust gases back through your engine. There is no "EGR", there are a bunch of parts making up the EGR system. If you read the FAQ you will see that various things go wrong with those parts. If you live in a state with emissions testing you may have to fix the system to pass your test. Even if you don't you may decide to fix it because you are anal or because you don't like the annoying check engine code all the time or you love the environment so much that the miniscule saving in nox emissions from the system is important to you or the idea of the truck not running with the designed fuel/air mix bugs you, or the idea that your air intake may be choked with carbon annoys you.