Error Code 25 and 26

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dthanh

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Hey just recently put a new exhaust system in my FJ62 from the O2 sensors back. Have the two pipes joining into one cat. Ive noticed signigicant loss of power especially at the low end - this was starting to occur while the cat was going but is worse now. After the new exhaust ran some injector cleaner through to see if it was clogged injectors. Still lack of power and worse-than-normal fuel economy. Driving today the Check Engine light came on and gave me a Error Code 25 (Air-fuel Ratio Lean Malfunction) as well as Error 26 (Air-fuel Ratio Rich Malfunction). Is this a problem with the O2 sensor or something else? Could this be a reason for lack of power and poor fuel economy? The 3F has 192,000 Kilometres on it.

Thanks
 
Is that a modified system where you got two pipes going into one cat? In the US there are two pipes going into two cats. I think that your cat might be blocked by too much exhaust entering the system. Try disconnecting the cat and see how the idle and power is affected when reving up the engine. How long ago did you put in the new exhaust system? Do you have black sooty exhaust residue? Has the O2 sensors ever been changed? At what speed did you get the engine code?
 
Thanks for replying. The exhaust is modified as you mentioned- the exhaust guy assured me that the (single) cat would be able to handle the exhaust that the two previous converters were. The exhaust is new within the last two weeks. The error code came after driving highway speed for about 10 minutes. The is black soot at the end of the (brand new) tailpipe. As far as I know, the O2 sensors have not been replaced.
 
No, my truck is EFI- although I've heard that its odd to have a FJ62 with an auto tranny but no power windows or door locks... But back to the subject, the O2 sensors are still in their stock positions 1:3 cycliners.
 
It seems that you are burning rich in fuel with the low fuel economy and the suspected black soot. I am suspecting that the cat still might be plugged up with too much soot or the O2 sensors are old and throwing off your fuel/air mixture. Both ways disconnect your cat and see how it runs( or complain to the muffler shop that installed the system that it is screwed up and ask them to disconnect it to trouble shoot it). How many miles does your truck have? I changed mine at 190k miles. If you got over 100k maybe you should change the o2 sensors because it will make it run better. I had the same similar problem with black sooty and bad fuel mileage with my 62 and found out it was a disconnected wire within the wire harness going to the air filter canister. If you or the mechanic messed around in that area you should double check within the harness if some of the wire got pulled back. check all vacuum connections because the mechanic could have disconnected something.keep us updated on the eventual solution.
 
tonkota said:
One cat is fine. As long as one oxy sensor is only reading from 3 cyl and the other ox sensor is reading from the other 3 cyl. Besides, the cat is after the sensors so the cat shouldn't have anything to do with a rich/lean condition.

Is your 3F carbed? I read someplace that the non-us 3F's were.
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I am thinking that if the flow is restricted thru the cats that this could throw off the O2 readings. Changing a system with two original cats and placing one could basically restrict the flow thus giving a "false" reading to the O2 sensors.Correct me if I am wrong because I don't know too much about exhaust systems. It seems that all these problems stem from changing the exhaust system.
 
dthanh said:
Thanks for replying. The exhaust is modified as you mentioned- the exhaust guy assured me that the (single) cat would be able to handle the exhaust that the two previous converters were. The exhaust is new within the last two weeks. The error code came after driving highway speed for about 10 minutes. The is black soot at the end of the (brand new) tailpipe. As far as I know, the O2 sensors have not been replaced.
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Did your muffler guy use the stock cat? or replace it with a new one? Could be that the O2 Sensor was hit or damaged during the install and now is sending faulty info to your ECM.

Test the O2 sensors (Both) or replace if they are original. I think this is your problem.

Good Luck,
G
 
mpetersrx7 said:
I had the ECU throw both of these codes also. Replaced both O2 sensors and still the problem persisted. What fixed mine was changing the FPR. Took a whole 10 minutes.

Hope this helps,
Mark
89FJ62
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FPR? What is the FPR?
 
FPR = fuel pressure regulator


dthanh - FSM scheduled maintenance inlcudes replacing O2 sensors at 128000KM. If you don't mind the expense, you might just go ahead and swap them out.

Bill
 
I sorted through a problem with those error codes a while back and found one of the cables to the O2 sensor was slightly chaffed by the auto transmission shift linkage, might look there also.
 
It seemed to me like it was one of the "Over-the-counter" fuel injector cleaners. I think it may have been STP or something similar. I added only the required amount per instructions and shortly after the light came on. It went off after the tank of fuel was run through and hasnt come back on since.
 
can I pad my post count :D
 
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