Check Engine Light - CEL

[kbrandsma]

During the winter of 2007-2008 I replaced my RMS and clutch and while I had my exhaust off I thought I would also replace my O2 Sensors. I made the mistake of replacing them with 4 Walker O2 sensors (with original fitment) and had nothing but problems with them. Since then on occasion I would get a CEL and after 4 to 5 drive cycles the CEL would eventually disappear. I would check with the Durametric and the codes where always P1117 and P1121 with P1115 and P1119 Pending. Several weeks ago, I received a notice to renew my license which also meant I would have to pass emissions testing.

I have owned my Boxster since July 2007 and it has 104K miles on it.

The CEL light was on so I checked the codes, I was surprised to find so many. They were P0410, P0411, P1125, P1123, P1117, P1121, P1115, P1119, P1130 and P1128. :eek:

A couple of weekends ago, I took some time and tried to systematically determine the problems. I ordered a change over valve from Sunset Porsche and a gas cap (I figured I could return the valve if it was not needed) and began to work. I replaced the gas cap. I noticed that the Secondary Air Pump was not working and checked the fuse. The 40 AMP fuse is located in the rear trunk underneath the relay bank on the driver's side. The fuse was burnt out and I replaced from Autozone for a couple of bucks.

I disconnected the battery, opened up the engine bay, removed the passenger side seat and front engine compartment and removed the change over valve by accessing it behind the alternator and under the passenger side fuel intake manifold. I have heard from some that accessing the change over valve from the top is the way to go by removing the fuel intake manifold. I chose not to as I also needed to replace my serpentine belt. A picture of my old valve is below. Based on what I found I determined it needed to be replaced.

I connected the battery, started it up and checked all the vacuum hoses by tightening them. I used starting fluid to systematically check for vacuum leaks at every connection. No leaks found. I closed everything up, took it for a ride then reset the codes. The CEL light returned. I commute 120 miles everyday and decided to drive a few drive cycles before continuing. The next time I ran the codes the following where found. P1123 and P1125 where the only ones that had gone. I assumed P1602 came from disconnecting the battery.

A couple days later I replaced the front O2 Sensors with my orginal ones that I removed several years earlier. Again I reset the codes and drove several drive cycles. This time I was down to only 4 codes P1128 and P1130, P1117 and P1121 as shown below:

I then replaced the rear O2 Sensors with my original rear ones and again erased the codes. After a couple of drive cycles I got the following two codes.

I then ordered a Air Mass Sensor from Autohaus for $182.57 shipped which seemed to be the best price out there.

Porsche Part Number for MY98 996.606.123.00 and Bosch Part Number 0-280-217-007

With 104K on the clock I figured it was a safe bet that the Air Mass Sensor was due to be replaced. The following weekend and with no codes I passed emissions!

Parts ordered from Sunset:

Cross Over Valve - 993.113.245.01 - $74.80

Fuel Cap - 996-201-241-03 - $9.61

YEAH! :jump:

Edited February 8, 2011 by kbrandsma

[Dale_K]

That's pretty interesting and congratulations on solving your problems and getting the car to pass the emission test. I guess I should get that Durametric gizmo. The 2000 S tip I bought a couple of months ago is running great but sooner or later I'll need something that will diagnose the codes.

BTW, what is the "change over valve"?

[kbrandsma]

That's pretty interesting and congratulations on solving your problems and getting the car to pass the emission test. I guess I should get that Durametric gizmo. The 2000 S tip I bought a couple of months ago is running great but sooner or later I'll need something that will diagnose the codes.

BTW, what is the "change over valve"?

Here is a good system analysis and excellent write-up from Mike Focke's web page. Link HERE