CEL light - diagnostic code P1128?

The subject says it all, my Check Engine Light went on over the weekend and the only code im getting on my Actron is P1128. Any thoughts are appreciated while I go look this up. Thanks

before this turns into a arguement you need to get fra/rkat (fuel trim) numbers to know which direction to go in. that fault does not mean replace the maf sensor regarless of what anyone says. It could be a maf but not 100%

Could you dumb that down a hair and tell me what the MAF sensor is?

The code is generated when the O2 sensor for bank 1 drops out of it's voltage range, indicating that the bank is running to lean. The most common cause of this code is an air leak in the untake system or the exhaust. Often a P1130 (bank 2) will follow eventually. There can be other causes, but the above are the most common. Check vacuum lines, intake tubing and throttlebody bolts. Make sure you have a good oil filler cap seal. If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. Remove and clean the MAF with electronic spray cleaner. The MAF sensor is the device inline with the air intake system that measures the amount of air passing into the engine and from that reading, the computer will add the appropriate amount of fuel. Often, if it is dirty, it reads less air than there actually is and the computer adds too little fuel.

I'd also take a look at the oil / air separator bellows for cracking. Replacing it cured all of my codes (as it cured a massive vacuum leak). 1999Porsche911 has offered good advice as well.

MAF = Mass Air Flow sensor. It does what 1999Porsche911 stated in the 3rd paragraph in post #4.

[/quote] If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. [/QUOTE] I have a CEL problem as well - usually cleaning the MAF solves the problem - but lately it comes back on much sooner - sometimes the same day. I thought a next good step would be to clean the idele control valve - but as a newbie would appreciate some help with description, location, any special issues with removal/replacement. TIA - Would be a good project on a rainy day like today.

I did not think you were supposed to use carb cleaner on the MAF but electronic cleaner????

If you have a 99 C2, remove and clean with carb cleaner, the idle control valve. [/QUOTE] I have a CEL problem as well - usually cleaning the MAF solves the problem - but lately it comes back on much sooner - sometimes the same day. I thought a next good step would be to clean the idele control valve - but as a newbie would appreciate some help with description, location, any special issues with removal/replacement. TIA - Would be a good project on a rainy day like today.[/QUOTE] In the picture below, the larger device (with the visable sticker) screwed into the left side of the throttlebidy is the ICV. Remove the cable and 2 screws to remove. Be careful with gasket as you will reuse it. Spray liberally with carb cleaner and make sure that the window inside it pivots freely. Jim

I do have a '99 C2 - Thanks - Looks like you removed the air box completely. While I'm in their, I may change some vac hoses - I saw some nice red ones at pep boys and thought it would ad a nice touch in addition to ensuring no air leaks.

your not going to be able to get to any vacum lines easily and on a 99 ID be very worry of them breakign when you tocuh them

How else do you determine if there is a vac leak setting off the CEL ?

There are various ways to test them using smoke, propane, etc, but I would simply visually check them out first. Most of the lines are easily accesable on the 99. The lines going to the vaccum canister above bank 1 can be easily tested by blowing into the line and making sure that it holds pressure. Make sure that the vaccum line from the first intake crossover tube is connected to the fuel pressure regulator on bank 2. Check 2 connections to electric changeover valve located above alternator. Check bolts on throttlebody and related tubing. It is unlikely that you have a large leak as one would throw more CEL codes and performance would be greatly affected. I would also throw in a bottle of injector cleaner to the gas, clean the throttlebody and intake with carb cleaner. Then reset the computer and give it another try.

"I would also throw in a bottle of injector cleaner to the gas, clean the throttlebody and intake with carb cleaner." Thanks - Any preferences on the injector cleaner ? or are they all the same ?

They're all pretty much the same.

"Spray liberally with carb cleaner and make sure that the window inside it pivots freely. Jim[/QUOTE] Jim/anyone: I have it apart - there seems to be alot of black soot inside. 1. The window does not pivot freely, after I clean it, should it move open/closed simply by moving the unit, or should it still need to be moved w/ a small item. 2. Can I spray carb cleaner into the throttle body ?? Or is this a big no no. Not sure how else to clean it out without removing the entire thrtle body and hand cleaning - larger project for another day. TIA

Carb cleaner works great to find vacuum leaks but I dont spray it all over the P-car with all of its plastic like I used to on the old Camaros I owned. Propane sounds better for our cars but I have never used propane, does it rev the engine as much as carb cleaner? I would think it would not since it is not as volatile.

Pulling the throttle body is not difficult. I did it, cleaned the IAC valve, and replaced it in my driveway one evening. Took a total of about an hour.

first you need to ckech your tra numbers and see if they show you as 2 rich or 2 lean, then if you have a vacum leak you go from there, i perfer using smoke from an evap machine but outside of the shop use a vacum guage

Just cleaned the IAC valve and part of the plenum that I could reach - filthy black soot - at some point I'll have to go back and take off the entire throttle body and give it a good cleaning - In the interim, after I started back up she was almost stalling when I gave it any gas. I massaged her up and after a run around the block and some rpm's, she's running smooth. Will have to wait to see if the CEL comes back I think I'm going to add some injector cleaner next time I'm close to empty - probably by tomorrow night. 99firehawk - This is new to me but I'm somewhat handy - "outside of the shop use a vacum guage" - I'll get a vac gauge - where exactly would I hook it up and what readings should I be looking for. TIA

i beleive that chevron techron is the only injector cleaner that porsche mentions.

the first thing you need to do is get your fra numbers and post them, you may be chasing a vacum leak that doesnt exisit, 1128 could be a lean or rich condition

What does one do for rich or lean condition??

If you're too rich, you take it to the dealer.If you're lean, go by the posts here and save your money!!

you need to figure out which it is and diagnose it from there