Advice for CEL coded P1128 & P1130 - Page 2 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

skip_168 · 04-14-2008, 04:01 AM

Quote:

Originally Posted by Topless

Wait a minute! Are we all barking up the wrong tree here? You have a 2000 MY 986 S? If so you have a 7.2 DME. Those fault codes are different. 1128, 1130 refer to O2 sensing idle range. This would rule out the MAF as the problem. Go to Renntech.org and search these codes for your specific car year and model. Sounds like a vacuum leak is more likely. Here is one thread for the same model range car: http://www.renntech.org/forums/index.php?showtopic=18257&hl=1128+1130+codes

once again another code definition..

and yes, a vacuum leak can cause the same codes.. on the list of things to check, vacuum leaks are first...

and actually the DME has much more diagnostic info available than you get to see. The car manufacturers are required to follow the OBDII code protocal & comunication standard if they want to sell cars in the US, but they dont put all the info in there..

you need to have the Porsche diagnostic tools, (which are propietary to Porsche), to see all the info there is..

Of course I haven't worked with car stuff since 2000, so alot could have changed since then...

2000SoCalBoxsterS · 04-14-2008, 05:09 AM

Quote:

Originally Posted by skip_168

once again another code definition..

and yes, a vacuum leak can cause the same codes.. on the list of things to check, vacuum leaks are first...

and actually the DME has much more diagnostic info available than you get to see. The car manufacturers are required to follow the OBDII code protocal & comunication standard if they want to sell cars in the US, but they dont put all the info in there..

you need to have the Porsche diagnostic tools, (which are propietary to Porsche), to see all the info there is..

Of course I haven't worked with car stuff since 2000, so alot could have changed since then...

Topless, according to my Bentley's service manual the codes are the same for the 7.2 DME in this case. From the research I've done in the Tech section of PCA.org the Tech's there point to the MAF or the Oil separator bellows. I also printed out the RennTech code definitions as a backup to my service manual and they are all the same. I was also confused or concerned that it might be the O2 sensors because that's what the P1128 & P1130 CEL codes mention. However, Hayjae made this very good point which is consistent with what the PCA Tech's are saying,

"The O2 sensors are just reporting the symptoms of the problem. Since they are the last sensor, there is so much upstream that could result in a O2 code. Cleaning the MAF may work, but if it doesn't, look for vacuum leaks. A vacuum leak could cause a rich condition. In addition to checking the usual tubing around the motor, check the oil cap, oil filler tube and oil dip stick. If that doesn't work, get a new MAF. It could be the air/oil separator, too."

It seems the consensus opinion from multiple sources is the MAF, Vacuum leak, and air/oil separtors also know as the oil separator bellows.

I did clean the MAF and changed my air filter at the same time. So far after an hour of driving no CEL. But I'll need to drive it some more before I feel confident that the problem has been solved.

BoxsterLewis · 04-14-2008, 09:25 AM

Dumb question, i used to go to Autozone and check my codes, probably cant with the Boxster huh?

dcporsche99 · 04-14-2008, 10:05 AM

Hey BoxsterLewis,

Yes, you still can have Autozone check your codes for you at no charge.

2000SoCalBoxsterS · 04-14-2008, 10:29 AM

Quote:

Originally Posted by BoxsterLewis

Dumb question, i used to go to Autozone and check my codes, probably cant with the Boxster huh?

Yes. I could have gone to AutoZone. But Auto Zone is a good 15 miles from my house. So I'd rather have my own handy code reader, find out what CEL codes I'm getting. Then research what they mean and the fix on PCA.org and here, and then go to AutoZone to buy the parts I need. Plus, I love gadets so I just had to have my own handy dandy code reader.

chris hankins · 05-05-2008, 11:09 AM

I just had the same codes pop up (1128, 1130) as socal2000, and I'm starting with cleaning the MAF thing and looking at the oil cap, other obvious vacuum leaks. @ questions:
1. Is there any real danger in driving my car while I get this thing figured out (note that I generally drive the car as it was intended, but am willing to back off in the short term)?
2. This is probably a stupid question, but after I clean the MAF, should I reset/clear the codes, or will the CEL just go off after a successful fix?

2000SoCalBoxsterS · 05-05-2008, 11:42 AM

I have now driven about 250 miles since I cleaned my MAF and changed my air filter and no CEL.

I have read on the PCA.org Q&A tech section that long term driving with your fuel air mixture being too lean or too rich due to a bad or dirty MAF can cause damage in that if it is too rich it can burn out your CATs.

I cleared my CEL with a code reader. I don't think the CEL will clear itself simply because the cause has been resolved.

AUDIOGUY · 05-05-2008, 04:42 PM

I cleaned my MAF and cleaned and re-oiled my EVO filter this weekend... car definately runs better. Smoother idle and no bogging out. CEL is back on now though. I may have a bad 02 sensor somewhere??

Who knows. I am not into going to have it looked at by a pro right now. I have a
feeling they wont know any more than myself.

skip_168 · 05-06-2008, 05:50 AM

Quote:

Originally Posted by chris hankins

I just had the same codes pop up (1128, 1130) as socal2000, and I'm starting with cleaning the MAF thing and looking at the oil cap, other obvious vacuum leaks. @ questions:
1. Is there any real danger in driving my car while I get this thing figured out (note that I generally drive the car as it was intended, but am willing to back off in the short term)?
2. This is probably a stupid question, but after I clean the MAF, should I reset/clear the codes, or will the CEL just go off after a successful fix?

It took me about a year with the CEL light on & off to finally get around to fixing it, and no damage occured.. not really a big deal, as long as you know what the codes are..

Yes you should clear the codes out after any repair. The ecu will turn it off if the code doesn't reset, but it takes like 500 key cycles or something like that..

skip_168 · 05-06-2008, 05:59 AM

Quote:

Originally Posted by AUDIOGUY

I cleaned my MAF and cleaned and re-oiled my EVO filter this weekend... car definately runs better. Smoother idle and no bogging out. CEL is back on now though. I may have a bad 02 sensor somewhere??

Who knows. I am not into going to have it looked at by a pro right now. I have a
feeling they wont know any more than myself.

Well, check the codes again.. If its the same ones, 1128 and 1130, the o2 sensors are kinda ruled out. you have four o2 sensors, two for each bank. one "upstream" of the cat, and one "downstream" of the cat... the chances of one sensor causing both banks to run lean are remote, and the odds of two or more sensors failing at the same time are remote as well.. Keep lookin for a common cause for both banks. Vacuum leaks & stuff. If all else fails, MAF replacement might be in order...

side note: dont forget to check the air tube from the maf sensor to the Throttle body. any cracks or leaks there, will also cause the lean condition. The MAF only measures air that flows across it. any air that gets into the engine behind the MAF will not be accounted for in the fuel delivery calculations...

eiblanco · 06-26-2008, 08:22 PM

I had a 1128 and 1130 error code and followed the advice of several posts and found that the oil filler cap was difficult to remove when running. I also heard an air leak after removing the rear engine cover. There were also a couple of instances of a lot of smoke coming from the exhaust at start-up only. So I changed the oil air separator and the CEL has stayed off since. The idle has improved and so has the gas milage.

Tony14 · 09-05-2011, 09:55 AM

Was getting 1128 AND 1130 codes from the CEL condition on my '99 2.5L Boxster. Took it to a pro and got the oil filler tube replaced. Within 75mi the CEL was back on throwing the same 1128 AND 1130 codes (both cyl. banks reaching rich threshold, in otherwords, running lean). I decided to try to figure this out myself. Consulted this and other forums. Replaced fuel cap. Still got 1128, 1130. Bought some MAF cleaner and spent about 45 min accessing the engine compartment, removing and cleaning the MAF (installed new air filter while I was in there, old one was clean but replaced it anyway) and putting it all bact together. Reset the codes with my Actron 9950 OBD II gadget and went for a spin. Codes have not returned thus far and I must say, my Boxster is running like it was new! A VERY noticable improvement in performance. Thanks for all the advice! The Forums are a great source for information. If codes return, I'll let you know.

1999 Boxster
51,800 mi.
Artic silver, Sport Package
Totally stock

fullthrottle52 · 09-08-2011, 05:14 PM

These codes have been discussed here many times.

Again, Go get a smoke test for any leaks. When I had these codes my indy found a leak in the oil fill tube. Light came back on again. Put in a new MAF and problem fixed. No CEL at this point. Probably both issues together were causing the CEL. You have to start somewhere and a smoke test is the place to start.

You do have to clear the codes to see if they will come back.
Cleaning the MAF does not work unless it is really dirty and looks like it needs cleaning. If you clean it, it may last for a couple of weeks. After several start and run cycles it more than likley will come back on.

mikesz · 03-11-2013, 05:54 PM

A new oil cap? I like that idea!

mikesz · 03-31-2013, 03:39 AM

Finally got a nice weekend in RI. Replaced the rear brakes, rotors, pads, sensors then went digging for the motor. Took out the air filter, it literally disintegrated as I was pulling it out. I have never seen an air filter so bad in all my life. I got my shop vac and vacuumed the cleaner box and put the new filter in. While I was in there took out the MAF and cleaned that also. Put everything back together, reset the CEL and drove around the Scituate reservoir for 90 miles and no CEL so tomorrow I take it to be inspected.