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Discussion Starter · #1 ·
Hi!

I found on internet loads of comment about this error code, but in my case the only bad thing is with fuel consumpiton - about 9-10 litres (!) for 100 km on motorway. Normaly it should be about 6-8 litres.

The error means: "P1128 is "Long Term Fuel Trim Too Lean". Which means the air/fuel mixture is leaner than the HO2S can compensate for."

Idle is working correctly (i think thats to do with MAF), engine start without any problems and overall car running smooth.

What can cause a bad fuel consumption? Is anything to do with a lambda (O2) sensor or it could be something else?
 

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A bad O2 sensor that is giving a false lean reading will tell the computer to give more fuel to correct it. If the reading is false it makes the car run way too rich and wastes fuel.

Miles
 

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Discussion Starter · #3 ·
QUOTE (JBimmolate @ Aug 11 2010, 05:43 PM) index.php?act=findpost&pid=348690
A bad O2 sensor that is giving a false lean reading will tell the computer to give more fuel to correct it. If the reading is false it makes the car run way too rich and wastes fuel.

Miles
Thanks for respond! Should I put a new O2 sensor by the front of engine or by the exhaust? or maybe should I change both of them? Which one is most important for fuel consumption?

I forgot to mention, air filter is in very good condition and oil filter was changed about 2000 miles ago.

regards
 

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The way the O2 sensors work is the computer reads them as a pair and looks for the difference between the 2 and adjusts the fuel consumption according to the readings. I would change them both since they have both been subjected to the same conditions & when one is starting to go bad the other will not be far behind.

Miles
 

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MAF can contribute, you can remove it and spray it off with some electrical cleaner or MAF cleaner. This should help if that is part of the problem.


Miles
 

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Discussion Starter · #7 ·
I changed o2 sensor by exhaust I will let know if thats helps. Mechanic check my exhaust, all o2, co2 % are on a very good level, so I hope it was only that sensor (was a little black when he took it out)
 

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Discussion Starter · #8 ·
after about 100 miles error came up again :wallbash:

I changed both o2 sensors and restart ECU, any other sugestions?
 

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One suggestion that I can make is that you probably have an exhaust leak. I had one throwing the code near the flexpipe, so I replaced it and the code cleared itself. That's all I can offer.

Scout
 

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Discussion Starter · #10 ·
QUOTE (Scout @ Oct 16 2010, 10:02 PM) index.php?act=findpost&pid=363929
One suggestion that I can make is that you probably have an exhaust leak. I had one throwing the code near the flexpipe, so I replaced it and the code cleared itself. That's all I can offer.

Scout
How can I check if exhaust is leaking? Its not noisy and just pased all test for o2, co2 emission.
 

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My 2001 Hyundai Accent is doing the same thing. Took it to mechanic who said I needed to replace the ECM (Engine Control Module) which will cost $900.00.
It seems like this is a pervasive problem with the 2001 Hyundai Accent. What I am afraid of is that the car will die as I attempt to cross our highway (oncoming traffic).
Has Hyundai enacted a recall on this problem? If not, I would think that they would want to fix this problem before a person is harmed or killed.
 
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