CEL Codes

[mjpalermo]

I have a 2000 Boxster Base with the 2.7 engine. My CEL is on with the following 3 codes. P1133, P1126 and P1118. It would appear with these codes I need a new MAS. Has anyone else experienced these codes and is the MAS replacement the correct fix?

Thanks so much.

[JFP in PA]

Originally Posted by mjpalermo

I have a 2000 Boxster Base with the 2.7 engine. My CEL is on with the following 3 codes. P1133, P1126 and P1118. It would appear with these codes I need a new MAS. Has anyone else experienced these codes and is the MAS replacement the correct fix?

Thanks so much.

I'd be interested to know how you determined that these codes indicate you need an new MAF, as none of them are MAF related codes. 1126 & 1133 are codes for an overly lean condition on both banks, indicative of an intake air vacuum leak. 1118 is for the down stream O2 sensor on bank 2 temperature, which could also be related to an overly lean condition as well.

[mesutter]

If it were an intake leak, I'd expect it to also trigger codes 1128 and 1130, which indicate a lean condition at idle. In my case, a small leak ONLY triggered 1128 and 1130. A defective or dirty MAF could send erroneous signals to the DME (ECU), telling it to lean out the mixture. There is a post on Rennlist indicating that in one case, changing the MAF did, in fact, solve this issue. Google "Porsche", "P1126" and "P1133".

[mesutter]

The P1118 code is the bank 2 after TWC O2 sensor, which is likely bad, but it could be a bad connection or a wiring issue.

[mikefocke]

Look for the cheaper solutions before throwing parts at the problem.

Any recent work? Anything not stock? All hoses snugged up and attached? Any sign of a hole in any of them?

The rearmost O2 sensors are not normally the ones to go first. They can be checked for resistance or shorts and there can be a fuse or wiring issue. They can also be swapped to see if the problem follows the part. If you have to replace, use Bosch parts as they are the ones Porsche buys. Use the ones with pigtails included.

The MAF is an expensive part (clean only with MAF cleaner).

[JFP in PA]

Originally Posted by mesutter

If it were an intake leak, I'd expect it to also trigger codes 1128 and 1130, which indicate a lean condition at idle. In my case, a small leak ONLY triggered 1128 and 1130. A defective or dirty MAF could send erroneous signals to the DME (ECU), telling it to lean out the mixture. There is a post on Rennlist indicating that in one case, changing the MAF did, in fact, solve this issue. Google "Porsche", "P1126" and "P1133".

Totally depends upon the year of the car and DME version; on a 7.2 DME the same codes indicate overly rich conditions, on a 5.2.2 the same codes are an overly lean condition per the factory OBD II diagnostics manual. And no, I have not idea why the did it this way, but that is the way they list them in the manual.

[JFP in PA]

Originally Posted by mesutter

The P1118 code is the bank 2 after TWC O2 sensor, which is likely bad, but it could be a bad connection or a wiring issue.

Or it can be overheated by a lean condition. In any case, I would not be changing it until the other issue is addressed, codes cleared, and you see if it returns; it may not.

[mesutter]

I'd carefully remove and clean the MAF first. Check the online videos for the procedure. Note that the connector clip(s) securing the harness are different between the early and late MAF. Yours is the late style and has one clip on the wide side of the plug. Some videos show the early style with 2 clips on the narrow sides. Do NOT follow the advice on one video to use a screwdriver to release the clip, you can break it. Instead, push down firmly on the connector to fully seat it, while pressing the release button and then pull up while continuing to hold the button in.

The whole removal and reinstall process is relatively easy, but you need a security T20 Torx bit to remove the screws. Harbor Freight has a set for $10, but if you buy it in the store, check the security bits to verify the hole is centered in the bit. I checked a half dozen, and all had some off-center holes, but in each set, it was on different bits. I made certain the T20 hole was centered on the set I bought. Also, I just got a Bosch MAF for under $200 delivered from one of the usual sources.

[mesutter]

Originally Posted by JFP in PA

Totally depends upon the year of the car and DME version; on a 7.2 DME the same codes indicate overly rich conditions, on a 5.2.2 the same codes are an overly lean condition per the factory OBD II diagnostics manual. And no, I have not idea why the did it this way, but that is the way they list them in the manual.

Don't believe that is correct. According to one poster, the belief the 1130 and 1128 codes are caused by a rich condition on some DMEs is due to a poor English translation by Porsche. The code is set when the mixture goes too lean to be corrected by the enrichment circuit ("beyond the rich threshold") I have a 7.2 DME, and my codes 1128 and 1130 were apparently caused by a disconnected vacuum line (at least, they did not re-occur after the line was reconnected).

I could be wrong, but a quick call to a Porsche service department could likely give us the straight scoop.

[JFP in PA]

It is correct, I have the Boxster factory OBDII service manual in front of me, on a 7.2 1128 and 1130 are the same codes for opposite banks which states, "fuel/air mixture is so rich that sensing is up to its limits attempting to lean it out", with probable faults of a leaking injector or fuel pressure being too high. The same two codes on a 5.2.2 DME states "fuel/air mixture is so lean that sensing has reached its limits attempting to richen" , with probable faults of an intake leak or low fuel pressure.

Stuff like this is why I caution people about making sure they have all the supplements for Porsche service manuals as the same codes can mean something completely opposite depending upon year, model, DME version, etc.

[mjpalermo]

how do you trouble shoot an intake vacuum leak

[JFP in PA]

Originally Posted by mjpalermo

how do you trouble shoot an intake vacuum leak

First, eyeball it for anything obvious, next go to a smoke machine.

[mesutter]

Originally Posted by JFP in PA

It is correct, I have the Boxster factory OBDII service manual in front of me, on a 7.2 1128 and 1130 are the same codes for opposite banks which states, "fuel/air mixture is so rich that sensing is up to its limits attempting to lean it out", with probable faults of a leaking injector or fuel pressure being too high. The same two codes on a 5.2.2 DME states "fuel/air mixture is so lean that sensing has reached its limits attempting to richen" , with probable faults of an intake leak or low fuel pressure.

Stuff like this is why I caution people about making sure they have all the supplements for Porsche service manuals as the same codes can mean something completely opposite depending upon year, model, DME version, etc.

l

Porsche Boxster service bulletin no. 9/00 1715, dated 12/22/2000, speaks to a potential cracked oil filler hose problem on 1997-2000 Boxsters. It lists the codes that might be experienced "as a result of the incoming secondary air" with a DME 7.2 as P1126, P1128, P1130 and P1133 (and with a DME 5.2 as codes P1123 to P1130).

Again, I can only speak to my own situation. Since I corrected the vacuum leak and cleared the Codes P1128 and P1130, they have not returned.

Of course, the true original source OBDII manual is the German version. Is there a German-speaking mechanic out there who has access to the German version to verify the translation?