Trouble with Oxygen sensors

[CoastMalone]

2003 BMW 330i with 110k miles

So a few days ago my CEL came on and I scanned it with my code reader and it was a bad o2 sensor for bank 2 precat. I replaced it today and drove it around for about 20 miles and the light came back on. I scanned it again and this time it's a bad o2 sensor for bank 1 precat. Is this just a unlucky coincidence or could there be something else I should look into? I haven't gotten a code for bank 2 so far after I replaced it.

Thanks!

[MarcoZandrini]

BMW considers O2 sensors to be maintenance items that need to be replaced at 100k mile intervals. It does seem odd that the other pre-cat sensor went bad right after replacing the other sensor. I’d replace it with a Bosch sensor and see what happens. Did you replace the valve cover gasket recently?

[CoastMalone]

BMW considers O2 sensors to be maintenance items that need to be replaced at 100k mile intervals. It does seem odd that the other pre-cat sensor went bad right after replacing the other sensor. I’d replace it with a Bosch sensor and see what happens. Did you replace the valve cover gasket recently?

Yeah I replaced bank 2 with a Bosch. The only other thing I've done to the car recently is change the spark plugs.

[por911]

I just did all 4 O2 sensors on our 02 330xi with 64k. They were acting up, sending codes into the ecu along with a slight roughness to idle. The roughness at idle went away after and the mpg went up, thankfully. The fact you got 100k out of them is amazing. I'd previously gone through our car and replaced the plugs, fuel pump, fuel filter/regulator, ccv & hoses, vac hoses, injector o-rings,motor mounts, and intake gaskets.
regards

[328 Power 04]

What was the exact code number?

[SloopJohnB]

I'm at 110k miles with OEM O2 sensors. Plug changes every 30K when valves adjusted S54 motor. Occasional serp belt and tensioner, one fuel pump, one fuel filter/pressure regulator at 90K, one guibo at 105K, still original clutch and pressure plate, one set of front/rear brake pads at 66K miles, factory reg oil and filter changes except for last 10 years every year at 6K miles or less. I have an oil level/temp sensor to change in the sump but I don't intend to change 02 sensors until/unless mileage or performance drops. Also have original convertible top....RaggTop once a year FTW!!!! Of course it helps that the car is generally garaged at home or work or commuter garage, but still. Trouble free except for factory recalls on both front airbags, conrod bearings (twice!...got free oil change with both of them), both door window regulators. Oh, yeah, the blower resistor assembly was pau, and the blower motor itself is making very slight noises, not squeal, but likely bearings. When it stops turning or gets squeaky i'll just change the entire blower motor/fan assembly.

[SloopJohnB]

2003 BMW 330i with 110k miles

So a few days ago my CEL came on and I scanned it with my code reader and it was a bad o2 sensor for bank 2 precat. I replaced it today and drove it around for about 20 miles and the light came back on. I scanned it again and this time it's a bad o2 sensor for bank 1 precat. Is this just a unlucky coincidence or could there be something else I should look into? I haven't gotten a code for bank 2 so far after I replaced it.

Thanks!

Unlucky coincidence most likely. I guess I'll have to pay attention to my 03 M3 w/110K miles on it....

[bluptgm3]

Ya O2 sensors are considered 100k mile replacement items. That said I’ve gone over 100k miles on two sets. Then replaced two due to codes, later discovered to be a dry 3 year old battery low on voltage.

BTW, NTK makes Bosch O2 sensors. Look closely at your Bosch sensors, they are most likely stamped NTK.


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[CoastMalone]

What was the exact code number?

P2240 was the original one for bank 2
P2237 was the new one for bank 1

[MIKYZZ4]

Check the o2 sensor heater circuit fuse in the fuse pack located underhood in the ECU fuse box.