P1117, P1121, Po131, Po151, Po137, Po157
 

Well, this could very well be my first post on the 986 Forum! Nothing like an introduction with problems. :rolleyes:

I picked up my 3rd 986 a couple of weeks ago. Been struggling with this one a little. MAF is 3 years old, cleaned it with warm water.

O2's are about 1 year old, I did replace one of them, all codes remain.

I've been checking the harness, cannot find any broken or shorted wires, but I'm still working on that.

Any other places to start looking?

Replace the MAF anyway? I ordred my OBDII cable so I can run the datalog. That'll help as well.

Thanks for any help,
Dan

Welcome to the Forum! :cheers:
And sorry you are already having problems. I don't mean to split hairs, but you said the error codes "remain". Did you reset the error codes after cleaning the sensors? The codes will not go away automatically once you fix it, you have to reset and see if it comes back.

Thanks for the welcome Rick.

Yes, I did clear the codes after each trial. First was the PO151 O2 sensor for a new one. Cleared codes, came back after that 10-15 minutes of driving. Next was really checking as much as I could for harnes failure, air filter is very clean, washed MAF with warm water, let dry, cleared codes, came back same amount of time and same codes.

This is my 3rd Boxster and I have a data logger, but my buddy lost the cable. I have another cable on order now.

Cats have 100k miles on them......but you'd think I'd be pulling the high temp on the O2's, not the low temp?

Plugs and terminals look clean.

Could be a MAF still?
Oil seperator?

I also have my brake wear light on with 4 new sensors. I'm a little concerned there is a harnes issue. I haven't checked it all for sure, only a few parts that pass through something. I'm hoping someone else has had this failure and can chime in with some good ideas where to keep looking.

-Dan

Year, model, and mileage?

Those are not mixture codes that indicate a bad MAF. More likely:
1. Water damage to harness or DME.
2. Rodent chewed/damaged harness.
3. Wrong O2 sensors for car.

Oh, sorry about that.

1997 2.5 5spd, no TC and no mods.

Yuck:

"A contact at BOSCH who make the sensors for Porsche admitted to me that there are differences (even though the part numbers are the same!) between the ones sold in the aftermarket in BOSCH boxes and the ones sold to Porsche in Porsche boxes or bags. A genuine sensor from Porsche costs between £300 and £500 depending on the engine model, and the Bosch ones are much cheaper. However, the Bosch items tend not to last as long, are made/calibrated to lower spec's and fail much sooner than the Genuine parts. Its even been said that the ones sold in Bosch boxes are often ones which have failed Porsche quality assurance testing. Also a Genuine item comes with a 2 year garauntee from Porsche, even if installed by an independent specialist."

I am starting to think this is my issue. Mine is over 30k miles old. I'll have to check the reciept.

After lots and lots of reading (I should be working) I've ordered a Bosch MAF, not the dealer one for $707, but one from parts store for $162. The dealer price of $707 is a little hard to swallow.

Seems my issues combined are pointing towards a failed or failing MAF. The ABS light along with the CEL codes certainly support this theory. I'll keep updates coming here.

Although the rodent or water theories carry a lot of merit. I'll start checking those as well.

Dan

Hey root,

Since you are in Seattle, next time you need OEM parts, talk to: http://www.****************************************************.com/

Pretty much everything I've ordered from them is half the price of Barrier. Last I checked Barrier charged 30% over the "list" price, and Sunset is way under list. Plus since they are in Oregon it only takes a day or two for stuff to show up UPS ground.

-james

Thanks! It's been years since I've had a WorldPac account so this helps a lot. :cheers:

New cable arrived:
 

I am using OBD-2 software which only has VW-Audi level codes beyond standard OBD2 codes.

Hooked it up, yup, all codes present, cleared them and ran a test on the O2's, they all passed.

I'll update when I get my MAF, re-clear codes and drive, log data.

Anyone have any other OBD2 software they could recomend?

New MAF installed today, cleared codes, 5 minutes into the drive they all came back. :(

Going to start looking deeper into the harnes.

I'll start with the DME next. I'll do some searching, it's under the pass seat? I'll look and see where it is.

-Dan

I am only someone who has little true knowledge but two things stick out. One, couldn't water getting into the electrical system via cleaning the MAF with water be a place to start and , two- I have had repeating codes that would occur when I was trying to sort out a problem and they never came on in 5 minutes of driving. I thought it would have to go through a certain # of drive cycles. I have tried to locate problems, clear the codes, drove it once and when I got back I would read pending coded. It would not as yet show up as a CEL but it was logged in. The short version is that it might be a DME problem. Ed

I took a look at the DME box today and cannot find any indication of water damage. I know it doesn't mean there isn't any or the DME box doesn't have issues, but it did make me happy everything around the DME and inside the rear trunk is really, really clean and no signs of water. I did remove it and plugged it back in some 30 minutes later. I haven't driven the car again yet, but I believe that resest codes by removing power from the box. Mostly I wanted to reseat the main DME connection. I'll drive and report back.

Re-seating the DME didn't do anything.

There are a couple DME units for sale, $200-300. I certainly don't mind paying for one, but the dealer asspect worries me a little. How much could they charge for re-coding it to match the car? Yuck.

I'll keep posting findings, or lack of. ;)

If your car is running well and no CEL with codes just drive the car to see if they re-appear. The DME is just a computer and like any computer it may go bezerk if water temporarily shorted your O2 sensor wires, but as it dries out it may be fine. Your unplug and reset may be all that was needed. You had several "short to ground" codes so water is a likely source of the problem.

The CEL did come back on after about 10 or so minutes of driving. I'll keep checking and posting updates.

I worry about the water damage, although I haven't found any evidence of it, I know it could be there.

-Dan

On my way into work this morning I noticed the CEL went out for a second, or part of a second, then back on. I've researched a little about bad grounds being issues. I've already cleaned the two back by the DME in the rear trunk, but know there is possible issues that might be coming from chassis to engine/trans. So I'll check those this week. I didn't have time this weekend to do anything to the little guy. I'll keep any updates posted as I can.

I'm still not ruling out a failed DME unit. I know capacitors can leak messing all sorts of things up. I'd rather not get another used DME unit. I sense frustrating times getting the immobilize-er(spelling?) re-coding done. Does anyone know of a place that rebuilds units? I don't mind having my Box out of service while the DME unit is rebuilt.

-Dan

This place advertises in PCNA Panorama magazine:

PorscheDME.com

Ad says they rebuild all DMEs including Boxster. For '97s they repair yours for $675 or sell on exchange for $975. Spendy. Yikes.

Vertex (****************************************.com) offers rebuilt ones for $299-$759, no details listed on their site. Based on my experience with their customer "service" and feedback I've gotten from people in the know about their remanufactured mechanical/electrical parts, I'd try the guys above first. I like to go with specialists for that kind of stuff anyway.

Thanks for the DME tip, I did find the website, yes, pricey, but 5 year warranty. Hopefully it isn't a DME unit.

I am running the CarCode OBD2 software which really isn't good for much of anything other than pulling the codes and clearing them. You can test the O2's which is nice, but I have noticed, the only O2 I can test is the one I replaced. Hmm, bank 1, position 1 is the pass, before cat right?

If that is true, maybe the 4 "new" ones installed just are not cutting mustard? I can smell it running rich at idle. Something isn't right. The one I did replace was direct fit Bosch from local parts store.

Sounds like a Durametric would be a worthwhile investment. I got mine (haven't had to use it yet), the non-pro version that can only be used for three cars, on craiglist for $170 with 2 car slots left. If you ever sell your car you'll probably be able to recoup at least half of the Durametric's cost. Good value IMO.

I've been eye-balling the Durametric for a little while now. Seems like a really useful tool.

I stuffed my big head under the Box last night looking for a ground strap I could clean contacts on. Couldn't find it? Maybe it's on the topside? I'll check that part soon. I've read here and there about ground gremlins causing all sorts of bizzare issues.

AOS tests good (Oil cap test) and is only 4 years old. Never smokes, ever that I've ever seen or could smell. But running a little rich. Could still be 3 bad O2's I guess? It doesn't make sense I couldn't test them, only the one I replaced could I test through the software.

I added a ground strap last night from the tranny to the chassis. I didn't clear codes or test drive until I went to work this morning. I should have cleared the codes (duh). Not that I think I fixed anything, but with each change I should test to see if it's corrected my large swath of codes.

I did notice the car seems to be a little smoother now. Especially when it comes to very lightly on-off throttle. It's not "jerky" anymore. Not like it was, but it's smoother.

So the ground strap did good, just how much I still have to find out.

documentation
 

Dan,

Go to here for essential documentation:

http://www.digital-kaos.co.uk/forums/f104/porsche-poses-2-42-install-cd-46838/

I couldn't get the system to install, but once the zip archives are unzipped, you can save all the English (EN) pdf's that are OBD2 related which contain troubleshooting information for all the codes -- stop searching in the dark and wasting your time!!!

BTW, don't ever clean a MAF sensor with soap/water -- CRC makes a spray cleaner for MAFs.

Regards,

paul

Very cool, thanks Paul.

I wound up replaced the MAF after my "cleaning" which truly was nothing more than water, and not much of that either.

It wasn't the MAF at all.

I'm still hopeful the codes aren't being caused by bad wiring or bad DME.

Since I can test the O2 I replaced, but none of the others, I did order up 3 more from GRP. They should be here by the weekend. I know, I know, shouldn't just throw parts at it. But I think it's a good set of variables to eliminate.

I'll keep the updates coming. - Dan

Bad/corroded wiring/connectors have their share of causing CELs to come on and should be inspected/tested with a good digital volt/amp/ohm meter (at least a 10 Mega ohm input impedance).

Regards,
paul...

Replaced the other 3 O2's today. Noticed the Bosch have shorter wires and better connectors.

CEL was cleared and after 60 minutes of driving didn't come back on. Won't say that I solved the issues yet. But so far so good.

CEL did come back on today, P0403, none of the original codes were present. Cleared just for giggles, took about an hour of driving and same P0403 code returned. I'll consider this issue closed now. Hopefully it'll make a good reference for someone else in the future.

On to the next code! :)

The P0403 is a generic code for an EGR system, and I didn't know that these engines had an EGR valve. Maybe someone else knows.

Regards,
paul...

With my Box having 103k on the clock and pretty much everything original, I plan to replace the following which will hopefully resolve the latest CEL:

993-113-250-03 - Crank case check-vent valve
996-113-245-01 - Change over vavle for air injection
993-113-245-01 - Cut off valve for air injection

All those will be around $200 and if they don't solve it:

996-605-201-01 - Purge vavle for fuel vapor canistor

And if I get desperate:

996-606-160-01 - Idle air control valve - like $300 or so.

The change over valve has an electrical connection on it, so I am hoping that is what is causing the CEL. We'll see. I'll post back results here.

Before I order anything though, I'm going to pull the lid this weekend and check hoses again, make sure things are clear and actually see if I have any of the above listed EGR related parts on my Box. It's a 97', so I can see Porsche using some 993 parts I guess?

Making progress!

P0403 is a code I have never seen on a Porsche :confused: . Are you sure?

Ultimately it is your car and your dough but if it was my dough I would verify the code, get a description of the fault involved and use the process of elimination to find and fix the problem. There are good online resources to help. If you are not comfortable doing this it might be money well spent to take your car to a qualified Porsche tech for a diagnosis. Otherwise you could blindly change out $2000 in parts and miss the problem completely... or end up with more error codes :o . It happens.

You got me scratching my head now. Pretty sure it was P0403, but that was using the local parts store OBD2 reader. I wouldn't have ordered any parts before really checking things as planned this weekend. I haven't hooked it up to my laptop at home yet. Maybe I'll do that tonight and make sure I'm reading the correct code.

I'll report back. - Dan

Derrrr, it's P0430, not 403. Just call me dyslex,,,,,dislexs,,,,,dys,,,,,oh never mind. :)

Not much research to do here other than replace the cat. Time to shop and probably just get both. I'm sure the left isn't far behind.

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For a P0430:

Possible fault cause
♦ Oxygen sensor ahead of and after TWC exchanged
♦ Valve lift fault
♦ Aged oxygen sensor after TWC
♦ TWC faulty

Regards,
paul...

Hey Yellowstonepart,

Porsche 戲汽車沒有柴油機 !

再見,

paul...

Paulv,

It's just a guess on my part, but after replacing all 4 O2's now and all the other CEL's gone with only the P0430 present. I can now test and pass all 4 O2's so I am hoping it's just a bad Cat. I would assume so since the PO ran with faulty O2's for almost 3 years! I'm sure the Right Cat is clogged (ruined) and the left isn't far behind.

I found a pair of good low mile cats for $350 shipped to me. The 4 O2's, MAF, 2 front tires and lots of other little maint items have left my Porsche fund a little dry. Gotta water the money tree for a bit. Meanwhile, I'm trying not to drive the car much.

Upates to come....when I get some more money. :D

That code is for Bank 2 which is the driver's side (Bank 1 has the #1 cylinder in it and would have the P0420 code). If you have a buddy who owns or has access to an exhaust gas analyzer, you could measure all the gases (NOx, CO, HC, O2, CO2) before and after the Cat to prove it bad (or good). BTW, running with bad O2 sensors will make the car perform lousy as well as destroy the cats. Attached a little tutorial about exhaust gases.

Regards,
paul...

This was a recent purchase for me (not my first Box though). It runs great and had no real notable change when the O2's were replaced other than the CEL's didn't come back. So there might have been a short in one of them? I didn't bother to test them after replacement.

420, right, sorry I was thinking engine orientation backwards, I should know that. I don't know anyone anymore that does the analyzing, but I'm sure I could track down a local shop that'd do it for a couple of bucks. Probably worth it. Why replace a cat when I may not need to?

Other thing I was going to try this weekend was swap O2's from side to side. See if I get a P0420 instead of a P0430. If I do, then I know one of my new O2's is probably bad.

So, still things to check. Good side is codes are different and there's only one now.

You didn't mention it but I'm assuming that you will be swapping the "after cat" O2 sensors from side to side, as these are the ones whose signal is compared to the "pre-cat" sensor to determine cat efficiency (a required readiness monitor under OBD2 mandates) and sets the P0420/30 code when the efficiency falls below a predetermined limit.

Regards,
paul...