# P0134 and P1128 on 99 Jetta 2.0L



## barlie (Apr 23, 2005)

I got these codes from the ECU for 99 VW Jetta 2.0L 4 Cyl
P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P1128(long term fuel trim, bank 1 system too lean). 
So in reading up it seems like its the front O2 sensor that is the cause of this trouble. Am I right ?
But why would it indicate a lean mixture ?
Do I need to repalce the MAF too ?
Thanks
/s


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## vasillalov (Nov 5, 2003)

*Re: P0134 and P1128 on 99 Jetta 2.0L (barlie)*

MAF!
Been there, done that!
Get a new one from http://www.1stvwparts.com
Part number is: *06A906461A*

After you install the new MAF sensor, go to the nearest VW shop or a buddy with a VAG-COM and have the code cleared!
EDIT:
Don't mess with the O2 sensor yet. When the MAF goes kaput, your ECu is getting confused and changes your fuel/air mixture. The things get really ugly, the O2 sensor detects that and triggers another code in the ECU. So fix the MAF only and then try again....


_Modified by vasillalov at 4:47 PM 4-23-2005_


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## jacetheace (May 13, 2004)

*Re: P0134 and P1128 on 99 Jetta 2.0L (vasillalov)*

I just got the exact same codes out of my 2000 2.0 jetta......... what does the MAF do and how does it break, it seems like it would be pretty easy to replace but does anyone have anymore incite on what the problem is ??????


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## barlie (Apr 23, 2005)

*Re: P0134 and P1128 on 99 Jetta 2.0L (jacetheace)*

I replaced the front O2 sensor. I got it from the dealer for $30 . (It varies by engine block code and mine was AEF I think). Pep Boys took $45 to install it.
Works like a charm now. Much better.
/s


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## Hagphish (Jul 8, 2004)

*Re: P0134 and P1128 on 99 Jetta 2.0L (barlie)*

it is so simple to replace that i would not spend a cent on installation. You simply plug the new one in.The MAF sensor tells your computer how much air is flowing throught your intake. It gets dirty from dust particles and other tiny things that pass through the air filter.


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## jacetheace (May 13, 2004)

*Re: P0134 and P1128 on 99 Jetta 2.0L (Hagphish)*

thanks for the info


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