Cat efficiency bank 1&2 and 02 Sensor 1 & 2 error codes

[mautzi]

you are probably right. they read the codes and its process of elimination. I still have the SES after changing the front and removing the battery. drove the car and still had the stutter probably, I could floor it and it feels like the car is cutting the Revs, feels like the throttle is closing on me.

maybe once I change the rear sensors, but seems like my process of elimination will take me to replacing the cat converter also.

anyone think I need a scanner/code reader to clear the codes or will disconnecting both battery cables for 20 minutes do it?

thanks everyone for your suggestions

[Weasel]

Originally Posted by mautzi

. drove the car and still had the stutter probably, I could floor it and it feels like the car is cutting the Revs, feels like the throttle is closing on me.


anyone think I need a scanner/code reader to clear the codes or will disconnecting both battery cables for 20 minutes do it?

thanks everyone for your suggestions

If it bogs down when you get down on it, then you likely will need cat converters, as they are getting clogged. The efficiency faults are just emmisions related, and have NO EFFECT on the way she runs. Just about the only other thing I can think of would be if you had a fuel pressure problem where the pump wasn't keeping up with full load, which would cause full throttle bogging and would be dumping extra fuel into the exhaust which could possibly cause the efficiency faults. But that would cause mixture faults as well from the upstream o2 sensors.

What you need to do is have the dealer that wants to replace them (or any shop of your choice) confirm the diagnosis by running an exhaust back-pressure test under loaded conditions to ensure that they are indeed clogged. (the tester screws into the ports for the upstream o2 sensors)

[Whoopitupinmo]

Would the o2 sensors cause the p0171 and p0174 codes

[Bismark]

IT IS VERY UNLIKELY THAT ALL 4 O2 SENSORS ARE BAD AT THE SAME TIME. IT IS UNLIKELY THAT 2 SENSORS GO OUT AT THE SAME INSTANT. I THINK YOU HAVE AN AIR LEAK PAST THE MAF. CHECK THE AIR HOSES AFTER THE AIR FILTER ALL THE WAY TO THE INTAKE MANIFOLD. LOOK CAREFULLY AT THE ROUND FAT BELLOWED AIR DUCT ( PART # 13-54-1-440-102 ). GOOD LUCK.

[Whoopitupinmo]

Thanks for the reply, I do know he has checked for air leaks. We will look again.

[mautzi]

update:

replaced the o2 sensors in the back but the cat is gone, the rear o2 sensors had crud built up on them from the Cats. I now need to find some Cats at a reasonable price. Man the 3.0 Cats are double the price of the 4.4. If anyone has experience changing the Cats in a 3.0 please jump in.

The rear sensors are loosened/unscrewed from underneath the passenger side but they go up into the engine and wrap around to the plugs which are on top of the engine. Remove the BMW covers and you'll see where the y connect.

Again, any help with experience, diagrams or where I can purchase replacement cats would be appreciated. Checked fleabay and found each side at about $500, I may start calling junk yards (i justw ant to get another year out of this car)

[jst2878]

Those cats should last at least 10 years if you don't go mud bogging or off roading

[X5Dawg]

Problem with the cats in the 3.0 X5 is their design. Essentially they are part of the manifold, so there are no aftermarket options out there unless you have someone fab one up for you. My shop told me they had to loosen the motor mounts just to get good access to swap them out.

About them lasting 10 years, not sure what kind of mileage you are talking about, but I had about 130K miles on my X (6-7 yrs old) when mine was replaced.

[Weasel]

I'd call the dealer anonymously and ask them if they have a 10 year 100,000 mile warranty on the cat converters. Not sure because I don't change them often at all, but for some reason I think I remember that. I might just be thinking about the seat occupancy sensors though. But definitely worth a call.

[X5Dawg]

Originally Posted by Bismark

IT IS VERY UNLIKELY THAT ALL 4 O2 SENSORS ARE BAD AT THE SAME TIME. IT IS UNLIKELY THAT 2 SENSORS GO OUT AT THE SAME INSTANT. I THINK YOU HAVE AN AIR LEAK PAST THE MAF. CHECK THE AIR HOSES AFTER THE AIR FILTER ALL THE WAY TO THE INTAKE MANIFOLD. LOOK CAREFULLY AT THE ROUND FAT BELLOWED AIR DUCT ( PART # 13-54-1-440-102 ). GOOD LUCK.

OK, this was actually some good advice. I recently had my tranny rebuilt a second time due to a faulty TC (no expense to me). Soon afterwards I had an SES light and it was diagnosed as 2 faulty O2 sensors which had been replaced a little over 30K miles ago. Dorve it home after the repair and next morning light was back on. Took it back and they said one of the new O2 sensors was faulty, so replaced. One week later, SES light is back, plus a high-pitched chirping noise upon acceleration. Got call this morning saying it is fixed - ended up an exhaust flange had been knocked loose apparently when they were reinstalling the tranny, so I did have an air leak as mentioned by Bismark, but way after the MAF.