CEL and codes

[Overdrive]

Hey, everyone. I just recently got my IMS retrofit and RMS fixed at a great independent Porsche shop here in CT, but a few days before I planned to drop the car there, the CEL came on.

This is the first time the light has ever come on in my year of ownership, with only about 2500 miles on it in that period of time. The car wasn't making any terrible noises or anything, the light simply came on at the end of my morning commute to work. I turned into the parking lot and the light came on about 2 seconds after that. So I had the shop come and pick up the car early and hold it at their shop until it was scheduled to be worked on.

When they began to work on the car they did a diagnostic for the CEL and were getting codes indicating a vacuum leak, and informed me that they suspected it could be a bad MAF rather than an actual leak. They did a leak test and found no leaks. Next they cleaned the MAF, cleared the light, and drove the car for at least a 40 mile commute, round trip. The light did not return and they finished the job for the IMS, RMS, rebalanced my tires which got rid of my steering shake, and I had them do my oil change since it was due anyways. They said if the light returned it may be a bad MAF and to replace that. The car ran great after getting it back, felt smoother than before (MOTUL oil must really be that good), but after driving home, parking, and then hopping in again after a short time to go to the local dealer to make a spare key, the light came back on.

I recently bought a MAF and air filter from PelicanParts and dropped them in yesterday. The MAF, at least the part that was in the hose and not out in the engine bay, was completely clean, but I remebered they'd just cleaned it at the shop, so I had to disregard its condition. Borrowing my friend's scanner, I cleared the codes after the installs and took the car on a good uneventful 80 mile drive over the next few hours. I parked at a Dunkin Donuts, ate some food for about a half hour at most, hopped back in and drove to the college campus down the road. I parked, and after about a minute of just idling, the light came back on.

So here are the codes I got after scanning it again:

P1117: Engine Coolant Sensor
P1121:: Throttle Position Sensor inconsistent with MAF
P1124: Throttle Position Sensor out of range
P0140: O2 sensor Bank 1, sensor 2

Prior to the MAF and air filter there were 6 codes, which I neglected to write down, and this time there were only 4, but I'm pretty positive they're 4 of the same from the original 6, so maybe there are multiple issues and the MAF replacement was still necessary.

I have not checked the coolant yet, as I just pulled up these codes today, but if anyone can provide some insight and troubleshooting recommendations, that'd be greatly appreciated. I'm not about to start throwing parts at the problem. Thanks in advance, and thanks for taking the time to read.

[Johnny Danger]

None of those codes really pertain to the MAF sensor. Why did your "indy" advise you otherwise ?

[Jager]

My Bentley book shows the P1117 alarm as a pre-catalyst O2 sensor cyl 1-3 heating alarm, how did you come up with a coolant alarm?

Throttle position alarms might be throttle position adaptation - Was the battery disconnected recently?

Your 0140 is post-catalyst O2 sensor alarm, could be loose connection. I would try cleaning the connector first. If that does not work swap with the other bank, this will tell you a lot.

[Overdrive]

Ok, reply time.

Danger: I honestly could not tell you what codes my indy pulled while he was working on it, though I may call him and see if he has them documented. What he told me was that the codes he was getting were indicating that the car was running lean, which led him down the path of finding a vacuum leak or seeing if the MAF was dirty and therefore sensing a leak when there wasn't one. Since the light hadn't come back on after he cleaned the MAF, he told me if it does come back on then the MAF likely needed replacing. I think it may have just not been driven quite far enough for the light to cycle back on. I was just listing the codes that I got after replacing the air filter and MAF and resetting the light this weekend.

Jager: Until I get my hands on a Bentley manual, I'll just have to live off of you guys and internet searching. My search for the P1117 brought up that coolant one, but I'm going to go by what you found in the book.

Yes, the battery was disconnected recently. It was done once at the shop while the car was getting the IMSR if I remember correctly, since the trip meter was at a lower mileage than when I left it and the clock was off time. It was disconnected again a few days later while the top was getting replaced, again because when I took the car back the trip meter was low and the clock was way off.

Thanks for the advice on the last code, I'll have to see what happens there. Hopefully I can get the car squared away before summer's out.

[Johnny Danger]

This link maybe helpful for you in the future .

http://www.iwantaporsche.net/BoxsterCheckEngineLightCodes.htm

[Overdrive]

Thanks, Johnny. So using that listing from Randall, here's what the codes I pulled note:

P1117 Oxygen Sensor Heating 1 After Catalytic Converter - Below Lower Limit

P1121 Oxygen Sensor Heating 2 After Catalytic Converter - Below Lower Limit

P1124 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold

P0140 Oxygen Sensor After Catalytic Converter (cylinders 1 - 3) - Interruption of Signal

So if I'm understanding this right, it all seems to be on the 1-3 side of the engine. That "Rich Threshold " code has me wondering, though. Is it reading rich because the other side is reading lean? Either way, aside from checking that the connection isn't just loose on one of the sensors, what could I be looking at here?