Oxygen Sensor-Check Engine Light Problem
 

I have a 98 Boxster that started showing the Check Engine Light. The Durametrics Program indicated that there was a misfire in Cylinder 1 and that the Oxygen Sensor was out of range in Bank 1 (Cylinder 1-3) and Bank 2 (Cylinder 4-6).

I replaced the 2 oxygen sensors for Bank 1 cleared the codes and everything was working fine. Engine sounded much better.

Problem: After driving about 800 miles the Check Engine Light comes on again. I hook up the Durametrics and get Bank 1 and Bank 2 oxygen sensor out of range.

Clear the codes and everything is runng fine for about 50 miles, then Check Engine Light comes on again.

Any ideas on my next step to analyze the problem and come up with a fix?

Engine sounds fine, but Durametrics indicates Bank 1 and Bank 2 oxygen sensor is out of range. I was thinking about replacing Bank 2 oxygen sensor, but haven't done that yet, but wonder why I'm still getting a reading that Bank 1 is still out of range.

Thanks for any suggestions

Just because an O2 sensor reads "out of range" does not mean it is bad, it is just reading out of range. The question then is why, and in which direction. If the sensor has "reached its enrichment limits", it mean it cannot make up for the O2 in the system with more fuel, or more plainly, you have a vacuum leak.

What are the codes you got?

The current fault codes from the durametric program are:

P1123 Oxygen Sensing Range 1 Cylinder (1-3)
P1125 Oxygen Sensing Range 1 Cylinder (4-6)

Thanks for guiding me JEP

Exactly what I thought, the codes indicate that both banks are running so rich that the DME cannot lean the engine out enough to get it into range. Most common fault: High fuel pressure (bad pressure regulator) or leaking injectors. As the codes are the same on both banks, I would start with a fuel pressure check.

JFP
Way to go !
Great long distance

Here is my current problem trying to analyze this: I'm 800 miles away from home where I have gauges and tools to start the troubleshooting.

Can I drive it home in the current condition?
What will I damage or what would I need to keep an eye on while driving?

Thanks for any input.

I would not rule out a vacuum leak......both banks running rich could me a leak between the maff and the plenum....the hard plastic ” flexible” vent pipes are notorious for getting brittle.
Id Pop off the service cover and see if you hear a his or see anything broken....

Running the car that far in an overly rich condition would not be a good thing as it could get worse, and I would be concerned about eventual fuel contamination of the oil.

How could an over rich condition beyond the capabilities of the DME to correct for stem from an intake vacuum leak, which should cause the exact opposite conditions?

I'm ready to get started testing the fuel pressure and I'm a handy newbie.

Any recommendations on the fuel pressure gauge tester to purchase?

Also, the sealing ring inside the brass cap needs to be replaced. Can I just get this at Advanced Auto or some local place, or do I need to get that from Porsche?

Actron makes a nice fuel pressure test gauge, but be sure to also buy the right angle adaptor which does not come with it and fortunately only costs a couple extra bucks. The Actron set up should cost less than $50.

Don't know if a regular parts store carries the correct size o-ring, we buy the entire cap by the bag full from a dealer.

majority of the times these faults are set is from a bad/contaminated maf.

None of the codes involved in this thread have anything to do with the MAF..........

Well I finally got around to testing the fuel pressure. For the last month I cleared the codes using Durametric Diagnostic Software and no check engine light appeared. The other day the check engine light came on so I decided to check the fuel pressure. The codes for the Durametirc software were P1125 Oxygen sensing range 1 Cylinder (4-6) and P1123 Oxygen sensing range 1 Cylinder (1-3).

I activated the fuel pump through the Durametric Software and the reading was 52 psi.

Also, here is another caveat which may or may not have something to do with the Check Engine Light. When using the Durametric Software it only allows me to access the Engine Option for ME5.2.2 for 1997-1999 which is fine. However, it won't allow me to access any other options like the ABS/DSC/PSM 5.3 for 1997-2001 or the Instrument Cluster K01 for 1997-2000 and it always tells me the cable is unplugged (even though it is not and the green light is on) for the Airbag, Air Conditioning, Alarm, etc.

I sent my cable back to Durametrics and they checked it and said it was something to do with my wiring.

Just thought I would throw in the Durametrics problem in case it maybe associated with the Check Engine Light and fuel mixture, but it is probably a problem for another thread.

Just following up to see if you resolved your two codes and how?
I have the same issues

Thanks

Resolution was cleaning MAF Sensor.

p1123
 

I have had a reoccurring code P1123 on an infrequent basis. Car is a 98 with 57,000 Kilometers or 36,000 miles. I have seen P1125 once only.
I purchased an Actron fuel pressure tester and have 55 PSI (3.8 Bar) with engine off. With engine running the pressure tester needle buzzes between 48 and 52 PSI (3.3 to 3.6 Bar).
Is this indicative of an injector issue where I should remove the injectors and have them tested or does this show a pressure regulator fault?
Ron