CEL Fault Codes

[tennis]

I have 1999 Boxster and recently had 3 CEL fault codes---mechanic replaced oil separator and cleared the codes. A few days later, I got three more codes p1602/p1123/p1125. I got those cleared again but decided to wait and see if they returned a third time...sure enough, they did a minute after putting the car in park to pick up my mail.

My mechanic says the codes could have many problem sources.

Can anyone please educate me on this annoying issue...was the replacement of the oil separator on its own the correct 'fix' or should something else also be replaced to prevent these codes from coming on? The car is running perfectly well otherwise. It only has 56,000 miles.

Is there an online list of these codes to be accessed?

Any help will be much appreciated.

[JFP in PA]

Let me guess: your mechanic cleared the codes by disconnecting the battery.......

P1602 is the code for memory loss of the DME adaption values. Usual suspects: Wiring issues at terminal 30, battery was disconnected, DME was unplugged.

P1123 and 1125 are the codes for both banks being so rich that the DME cannot compensate. Usually this is caused by high fuel pressure or leaking injectors; but as it seems to have happened just after the AOS was changed out, it may just be the lack of adaptation values (running time) on the DME.

If your mechanic did clear the codes by using the battery, first you need a new mechanic. That is not how you clear codes. Take the car to a shop with either a Durametric system or a PST II/PIWIS unit, re-read the codes and then have them cleared. If there really is a fuel issue, the 1123/25 codes will return without the 1602 code after the DME has relearned the adaptation values, which will require you to drive the car for a bit.

[infocusf8]

What caused your mechanic to replace the AOS? Was there a code indicating it had failed and or were you getting smoke from the tail pipe?

[tennis]

I have 1999 Boxster and recently had 3 CEL fault codes---mechanic replaced oil separator and cleared the codes. A few days later, I got three more codes p1602/p1123/p1125. I got those cleared again but decided to wait and see if they returned a third time...sure enough, they did a minute after putting the car in park to pick up my mail.

My mechanic says the codes could have many problem sources.

Can anyone please educate me on this annoying issue...was the replacement of the oil separator on its own the correct 'fix' or should something else also be replaced to prevent these codes from coming on? The car is running perfectly well otherwise. It only has 56,000 miles.

Is there an online list of these codes to be accessed?

Any help will be much appreciated.

Edited August 20, 2011 by tennis

[tennis]

Let me guess: your mechanic cleared the codes by disconnecting the battery.......

P1602 is the code for memory loss of the DME adaption values. Usual suspects: Wiring issues at terminal 30, battery was disconnected, DME was unplugged.

P1123 and 1125 are the codes for both banks being so rich that the DME cannot compensate. Usually this is caused by high fuel pressure or leaking injectors; but as it seems to have happened just after the AOS was changed out, it may just be the lack of adaptation values (running time) on the DME.

If your mechanic did clear the codes by using the battery, first you need a new mechanic. That is not how you clear codes. Take the car to a shop with either a Durametric system or a PST II/PIWIS unit, re-read the codes and then have them cleared. If there really is a fuel issue, the 1123/25 codes will return without the 1602 code after the DME has relearned the adaptation values, which will require you to drive the car for a bit.

You are absolutely correct...the mechanic told me he had to replace my battery after the repair, even though the one I had was only a few months old... why would that have been necessary...would they have somehow just drained it.. so would account for the DME issue.I will have the codes reread as you suggest.What do 1123/25 indicate and how do you finally get rid of them? What is O2 sensor connection as indicated on the printout? Is it damaging to the engine to drive the car in the meantime?

I should say that the mechanic originally ran a smoke test and found another leak after AOS was replaced.

The second clearing of the codes was not done via battery, as I did not have to reset my radio code that time.

The codes were printed from Durametric software as I have the printout.

The initial testing, AOS replacement cost me $725 including oil and filter change--5 hours of labor was charged.

Edited August 20, 2011 by tennis

[tennis]

What caused your mechanic to replace the AOS? Was there a code indicating it had failed and or were you getting smoke from the tail pipe?

The first codes were related to o2 sensors in all four cylinders...'lean limit' readings...he replaced AOS and ran a smoke test,found a separate leak which he maintains he also repaired.

What I do not understand is why these codes are still reading out even after this repair...what do they actually mean?

[JFP in PA]

The mixture codes may simply be "ghost" codes caused by a lack of adaption values in the DME. I would clear the codes using something like the Durametric, or any OBDII scanner, and drive the car for a bit before doing anything else. The mixture codes may come back again, so be prepeared for one more "reset" before taking them seriously.

[tennis]

The mixture codes may simply be "ghost" codes caused by a lack of adaption values in the DME. I would clear the codes using something like the Durametric, or any OBDII scanner, and drive the car for a bit before doing anything else. The mixture codes may come back again, so be prepeared for one more "reset" before taking them seriously.

Thanks for your helpful input...I will do that and hope fully that will be the end of them!!! :clapping:

[infocusf8]

I have 1999 Boxster and recently had 3 CEL fault codes---mechanic replaced oil separator and cleared the codes. A few days later, I got three more codes p1602/p1123/p1125. I got those cleared again but decided to wait and see if they returned a third time...sure enough, they did a minute after putting the car in park to pick up my mail.

My mechanic says the codes could have many problem sources.

Can anyone please educate me on this annoying issue...was the replacement of the oil separator on its own the correct 'fix' or should something else also be replaced to prevent these codes from coming on? The car is running perfectly well otherwise. It only has 56,000 miles.

Is there an online list of these codes to be accessed?

Any help will be much appreciated.

First off I'd find another mechanic.

That being said code P1602 is a voltage supply code and is probably what caused him to replace the battery but that code doesn't mean the battery is bad it just means there is low voltage triggering a code and the low voltage could be happening in the system not the battery.

P1123 and P1125 are oxygen sensing problems in the cylinders causing the ECU to sense a lean mixture threshold. None of these codes are a reason to change the AOS. If the AOS goes bad it is accompanied by smoke continuously coming out of your tail pipe. Lots of smoke.

Porsche codes are both good and bad. They are good because they tell you that a problem has come up in your car and/or that a problem is imminent. The codes are bad because they do not point to a specific part but to a system i.e. the emissions system which is the most common system in the car that will cause codes because the ECM is constantly adjusting air fuel mixture according to octane, air intake, altitude, what the O2 sensors sniff from the first set to the second set and etc. If something changes in the system, for instance a vacuum leak in the secondary air system, another common emissions code and CEL puller, you will get codes that indicate you have a problem in the system. It is why Porsche has developed a diagnostic "tree" to follow to narrow down the specific part{s} that have failed or will be failing. Shotgun mechanics either don't know the tree or get lazy and don't want to diagnose it so they start replacing parts hoping they get the right one. Problem is you pay for it in, sometimes, needless part replacement and returning codes.

Find a mechanic who knows the diagnostic tree and knows how to use it you will save yourself a lot of grief.

[tennis]

I have 1999 Boxster and recently had 3 CEL fault codes---mechanic replaced oil separator and cleared the codes. A few days later, I got three more codes p1602/p1123/p1125. I got those cleared again but decided to wait and see if they returned a third time...sure enough, they did a minute after putting the car in park to pick up my mail.

My mechanic says the codes could have many problem sources.

Can anyone please educate me on this annoying issue...was the replacement of the oil separator on its own the correct 'fix' or should something else also be replaced to prevent these codes from coming on? The car is running perfectly well otherwise. It only has 56,000 miles.

Is there an online list of these codes to be accessed?

Any help will be much appreciated.

First off I'd find another mechanic.

That being said code P1602 is a voltage supply code and is probably what caused him to replace the battery but that code doesn't mean the battery is bad it just means there is low voltage triggering a code and the low voltage could be happening in the system not the battery.

P1123 and P1125 are oxygen sensing problems in the cylinders causing the ECU to sense a lean mixture threshold. None of these codes are a reason to change the AOS. If the AOS goes bad it is accompanied by smoke continuously coming out of your tail pipe. Lots of smoke.

Porsche codes are both good and bad. They are good because they tell you that a problem has come up in your car and/or that a problem is imminent. The codes are bad because they do not point to a specific part but to a system i.e. the emissions system which is the most common system in the car that will cause codes because the ECM is constantly adjusting air fuel mixture according to octane, air intake, altitude, what the O2 sensors sniff from the first set to the second set and etc. If something changes in the system, for instance a vacuum leak in the secondary air system, another common emissions code and CEL puller, you will get codes that indicate you have a problem in the system. It is why Porsche has developed a diagnostic "tree" to follow to narrow down the specific part{s} that have failed or will be failing. Shotgun mechanics either don't know the tree or get lazy and don't want to diagnose it so they start replacing parts hoping they get the right one. Problem is you pay for it in, sometimes, needless part replacement and returning codes.

Find a mechanic who knows the diagnostic tree and knows how to use it you will save yourself a lot of grief.

Thank you so much for taking the time to give me such a detailed response....I will certainly find a new mechanic, although this one specializes in German cars.....I guess that doesn't really seem to count for much.

I did not have any smoke problem from the tail pipe prior to the AOS replacement...I am sure of that.

P1602 occured after battery was replaced.....that is even weirder.

I will get this third set of codes read and see if there is any change from last two readouts and take it from there.

I will post the outcome!

Thanks again!