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Check Engine Light Code 25 And 26, Related To Code 71?


hondaspeed85

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I have a 1992 LS400

Ok, heres the situation, the other day I got a Check engine light and it was code 71 (EGR). The car was hesitating throughout the RPM range, and idled rough (as if 1 of the cylinders wasnt firing.)

Cleaned out the EGR and cleared the code from the ECU. Car still ran rough, and the check engine light came back on about 10 miles later.

I checked the codes and I dont have the code 71 anymore, but now I have a code 25 and 26 (didnt have it before when i had the code 71). Which I read up on and usually that means replacing the o2 sensors.

Now, Would the code 25 and 26 have any corrolation with the code 71? I just want to know for sure before I spend the money on 4 new o2 sensors.

Is it possible for all 4 o2 sensors to start to go out all at once, hence giving me a code 25 and 26?

Also, would replacing the o2 sensors fix the code 25 and 26, or could they be related to something else?

Any help is appreciated, thankyou!

By the way, the codes are :

25 - Air-fuel ratio lean malfunction

26 - Air-fuel ratio rich malfunction

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I have a 1992 LS400

Ok, heres the situation, the other day I got a Check engine light and it was code 71 (EGR). The car was hesitating throughout the RPM range, and idled rough (as if 1 of the cylinders wasnt firing.)

Cleaned out the EGR and cleared the code from the ECU. Car still ran rough, and the check engine light came back on about 10 miles later.

I checked the codes and I dont have the code 71 anymore, but now I have a code 25 and 26 (didnt have it before when i had the code 71). Which I read up on and usually that means replacing the o2 sensors.

Now, Would the code 25 and 26 have any corrolation with the code 71? I just want to know for sure before I spend the money on 4 new o2 sensors.

Is it possible for all 4 o2 sensors to start to go out all at once, hence giving me a code 25 and 26?

Also, would replacing the o2 sensors fix the code 25 and 26, or could they be related to something else?

Any help is appreciated, thankyou!

By the way, the codes are :

25 - Air-fuel ratio lean malfunction

26 - Air-fuel ratio rich malfunction

Just read your post. You said that you cleaned the EGR Valve. What did you clean it with? Cleaning the EGR or any of the components where the fumes from the cleaner can get to it, can trigger these codes. The o2 sensors are very sensitive and the residue from certain cleaners affect them to the point of triggering the codes. Clear the codes and give it time to dry out completely. I replaced my o2 sensors on another vihicle. No codes. Later cleaned the EGR valve and got the code for bad o2 sensor. Cleared the code and drove it. Code came back but I gave it some time to dry out real good and clearer the code again. This time ran without any codes. This is only a possibility of might have happened when you cleaned your EGR.

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UPDATE:

Its funny that you post that because just before I read your post, I took my car for a drive and 1 or 2 minutes into the drive, the check engine light turned off. After that, the car ran perfectly fine. I drove it hard for a few bursts and the car seemed to run fine.

Got back to work and as I was parking, the car felt a little rough again, again it feels like a cylinder is misfiring or something. This time no check engine light at all though. Do you think that all of these problems stem from just having to change the sparkplugs, wires, caps and rotors?

I was thinking maybe 1 cylinder is misfiring, therefore sending too much unburnt fuel through the EGR causing it to set off the Code 71, which in turn set off 25 and 26 because of me cleaning it. Does that make any sense?

I just bought the car recently and havent done the normal Sparkplug/caps/rotors/wires yet, so I dont know when the last time they have been replaced. Would it make sense that this would be the problem?

'

Thankyou for any help you can provide.

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UPDATE:

Its funny that you post that because just before I read your post, I took my car for a drive and 1 or 2 minutes into the drive, the check engine light turned off. After that, the car ran perfectly fine. I drove it hard for a few bursts and the car seemed to run fine.

Got back to work and as I was parking, the car felt a little rough again, again it feels like a cylinder is misfiring or something. This time no check engine light at all though. Do you think that all of these problems stem from just having to change the sparkplugs, wires, caps and rotors?

I was thinking maybe 1 cylinder is misfiring, therefore sending too much unburnt fuel through the EGR causing it to set off the Code 71, which in turn set off 25 and 26 because of me cleaning it. Does that make any sense?

I just bought the car recently and havent done the normal Sparkplug/caps/rotors/wires yet, so I dont know when the last time they have been replaced. Would it make sense that this would be the problem?

'

Thankyou for any help you can provide.

You say that you drove it hard. How hard? Flooring it? How many miles on the car? Any of those things you mention can have an effect on performance. Could be an ejector malfuctioning but remote. Spark plugs misfireing? coil or wire breaking down? Or a combination? The computer detects all of these. If the car has a lot of miles and has not had preventive maintainence or little maintainence, these things can contribute to it's performance.

!Removed! luck and post your results so that others can benefit. A fix for one car does not neccessarily mean it will fix another.

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The car has about 150,000 miles on it. Im going to replace the Caps, rotors, plugs and wires tonight (even if this doesnt solve the problem, I should do it anyways.) And I'll post another update on the problem. I have been searching through tons of threads, and a lot of people have similar problems but it could be a number of things...

I'm thinking of replacing the coils too, since I doubt they have been changed and the car IS 15 years old...

And by driving hard, I mean flooring it, I floored it up to about 80-90ish on the freeway. And hard accellerated a few more times around the block.

EDIT:

I forgot to mention, at idle it will miss slightly, but when I turn on the A/C it gets worse. Also, if I put it into gear it'll get worse. So it gets worse under load...

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Must be the season! I have a 1990 LS400, 155m. My CEL came on for the first time ever today and I just finished reading the diagnostic code and it was 71, EGR sensor signal.

Could you describe what you did to clean out the EGR? And how do you clear the code from the ECU?

There is no rough idling with my car, no noticeable difference between before and after the CEL.

Thanks,

glenmore

1990 LS400

1991 300CE

2000 C280

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Must be the season! I have a 1990 LS400, 155m. My CEL came on for the first time ever today and I just finished reading the diagnostic code and it was 71, EGR sensor signal.

Could you describe what you did to clean out the EGR? And how do you clear the code from the ECU?

There is no rough idling with my car, no noticeable difference between before and after the CEL.

Thanks,

glenmore

1990 LS400

1991 300CE

2000 C280

Hi, I followed the directions that are on this site to clean the Vacuum Modulator

http://www.lexls.com/tutorials/emission/egrfilter.html

I also went as far as to take off the actual EGR Valve. If you look at a side view of the EGR valve, youll see its only held on by 2 nuts. All you have to do is unbolt those 2 nuts, and un hook all the lines that go to it. REMEMBER THE LOCATIONS OF ALL THE HOSES YOU UNHOOK! Dont be afraid if you see coolant coming out of 2 of the hoses, the EGR Valve is cooled by engine coolant. Once you get the valve off, spray it down with carb cleaner or brake cleaner. I sprayed mine down with brake cleaner a couple of times and cleaned it out as much as I could.

There was a more in depth tutorial about cleaning the EGR, It was either on this site of Clublexus.com. Either way, there should be a lot of information on this between these two forums.

After all that, to clear the CEL, open up the fuse box under the hood (its toward the driverside front). Pull out the 20A fuse that belongs to the EFI, wait about 5 minutes, then plug the fuse back in and you should be good to go.

www.lexls.com has a LOT of info/tutorials if you ever need them.

Goodluck!

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UPDATE:

So last night i changed the plugs, wires, caps, and rotors (OH MY GOD WHAT A PAIN!). The car purrs like a kitten now! Turns out, none of those things have ever been changed in this car! For 149000 I would have thought any decent person would have changed them AT LEAST once in the life of the car! I looked at every single screw/bolt/nut and it looks like none of them had been touched ever (along with the timing belt, but thats a different story <_< ).

Long story short, I think that solved all my problems. I cleared the codes and went for a spirited drive, drove it hard again a few times and the check engine light didnt come on, and the car still runs silky smooth. What a relief!! *crosses fingers hoping the problem doesnt come back*

Anyways, anyone with the problems I had (code 71, 25, and 26), check your plugs, wires, etc. because it's another possible solution to this problem. I was talking with my older brother and he said what I was thinking made sense. That is, since it was running with 1 dead cylinder, too much unburnt fuel was sent through the EGR, which made it throw the code 71, and because of that unburnt fuel it also threw off the o2 sensors, which made them throw code 25 and 26.

P.S. If I dont update this post in a few days, that means the problem is officially solved *crosses fingers* :cheers:

Thanks for your help guys, hope this post helps others :D

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UPDATE:

So last night i changed the plugs, wires, caps, and rotors (OH MY GOD WHAT A PAIN!). The car purrs like a kitten now! Turns out, none of those things have ever been changed in this car! For 149000 I would have thought any decent person would have changed them AT LEAST once in the life of the car! I looked at every single screw/bolt/nut and it looks like none of them had been touched ever (along with the timing belt, but thats a different story <_< ).

Long story short, I think that solved all my problems. I cleared the codes and went for a spirited drive, drove it hard again a few times and the check engine light didnt come on, and the car still runs silky smooth. What a relief!! *crosses fingers hoping the problem doesnt come back*

Anyways, anyone with the problems I had (code 71, 25, and 26), check your plugs, wires, etc. because it's another possible solution to this problem. I was talking with my older brother and he said what I was thinking made sense. That is, since it was running with 1 dead cylinder, too much unburnt fuel was sent through the EGR, which made it throw the code 71, and because of that unburnt fuel it also threw off the o2 sensors, which made them throw code 25 and 26.

P.S. If I dont update this post in a few days, that means the problem is officially solved *crosses fingers* :cheers:

Thanks for your help guys, hope this post helps others :D

I just did the caps/rotors/plugs/wires for the first time (202K)

What did you do to facilitate getting the caps/rotors out/in as regards the lower shield? I undid the bolts on the lower shields and bent them out of the way, but there has to be a better way?!?

Also, with the caps I used (Beck/Arnley) the rubber buttons (2 per cap) had come off at some point in working the cap into place. I found all but 1. Worst case is that it fell down into the timing belt area. If so, hopefully it will settle to the bottom to be found some time later when I have to do the timing belt.

Joe

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UPDATE:

So last night i changed the plugs, wires, caps, and rotors (OH MY GOD WHAT A PAIN!). The car purrs like a kitten now! Turns out, none of those things have ever been changed in this car! For 149000 I would have thought any decent person would have changed them AT LEAST once in the life of the car! I looked at every single screw/bolt/nut and it looks like none of them had been touched ever (along with the timing belt, but thats a different story <_< ).

Long story short, I think that solved all my problems. I cleared the codes and went for a spirited drive, drove it hard again a few times and the check engine light didnt come on, and the car still runs silky smooth. What a relief!! *crosses fingers hoping the problem doesnt come back*

Anyways, anyone with the problems I had (code 71, 25, and 26), check your plugs, wires, etc. because it's another possible solution to this problem. I was talking with my older brother and he said what I was thinking made sense. That is, since it was running with 1 dead cylinder, too much unburnt fuel was sent through the EGR, which made it throw the code 71, and because of that unburnt fuel it also threw off the o2 sensors, which made them throw code 25 and 26.

P.S. If I dont update this post in a few days, that means the problem is officially solved *crosses fingers*:cheers:

Thanks for your help guys, hope this post helps others :D

I just did the caps/rotors/plugs/wires for the first time (202K)

What did you do to facilitate getting the caps/rotors out/in as regards the lower shield? I undid the bolts on the lower shields and bent them out of the way, but there has to be a better way?!?

Also, with the caps I used (Beck/Arnley) the rubber buttons (2 per cap) had come off at some point in working the cap into place. I found all but 1. Worst case is that it fell down into the timing belt area. If so, hopefully it will settle to the bottom to be found some time later when I have to do the timing belt.

Joe

Actually I did the same thing with the shields you are talking about. I just bent them out of the way and squeezed my giant hands in there haha. The driverside was a pain because of the stupid radiator hose. So as i was bending the shield, I also had to hold the radiator hose out of the way and at the same time undo the very bottom screw of the cap (You know which one im talking about).

Also, another easy way to take out the old dist. caps is to take a pair of pliers, and break off the 2 nipples on the dist. caps that have the little rubber caps on them. ONLY BREAK IT OFF THE OLD ONES, this is to make it easier to access the bottom dist. cap screw, and also to make more room to pull the old cap out. For some reason putting the new cap it was a breeze. DO NOT BREAK THE NIPPLES OFF THE NEW CAPS of course.

I wouldnt worry about that rubber cap that fell, its probably settled down at the very bottom. I actually dropped a screw down there :cries: After that, I started stuffing shop towels underneath the Distributor cap just in case anything else dropped, it wouldnt go all the way down into the timing belt housing.

Even though im very mechanically inclined, when it comes time to change the timing belt, I'm just going to pay a shop to do it. My time is worth more than doing that job LOL

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Cleaning your throttle body may help solve a rough idle problem.

lht

UPDATE:

Its funny that you post that because just before I read your post, I took my car for a drive and 1 or 2 minutes into the drive, the check engine light turned off. After that, the car ran perfectly fine. I drove it hard for a few bursts and the car seemed to run fine.

Got back to work and as I was parking, the car felt a little rough again, again it feels like a cylinder is misfiring or something. This time no check engine light at all though. Do you think that all of these problems stem from just having to change the sparkplugs, wires, caps and rotors?

I was thinking maybe 1 cylinder is misfiring, therefore sending too much unburnt fuel through the EGR causing it to set off the Code 71, which in turn set off 25 and 26 because of me cleaning it. Does that make any sense?

I just bought the car recently and havent done the normal Sparkplug/caps/rotors/wires yet, so I dont know when the last time they have been replaced. Would it make sense that this would be the problem?

'

Thankyou for any help you can provide.

You say that you drove it hard. How hard? Flooring it? How many miles on the car? Any of those things you mention can have an effect on performance. Could be an ejector malfuctioning but remote. Spark plugs misfireing? coil or wire breaking down? Or a combination? The computer detects all of these. If the car has a lot of miles and has not had preventive maintainence or little maintainence, these things can contribute to it's performance.

!Removed! luck and post your results so that others can benefit. A fix for one car does not neccessarily mean it will fix another.

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