Just got this car, a BMW Z3 3.0 from a Tampa dealer and have not even had it 10 days and Check Engine Light came on. I wanted to get the oil changed to full synthetic just in case it wasn't and also to check the codes so I went to this fast oil-change place, a large chain establishment with good reviews.

The young kid there seemed to know what he was doing so I thought nothing of it. When they checked the computer the code came up for camshaft sensor. So I took it in the next day and they fixed it supposedly.

And it seemed to have a ton more horsepower but that CEL came back on. Something told me to check the oil... I had noticed an oil spot on the driveway about as big as a soup dish. Well they had overfilled it. How much blew out through the exhaust or wherever excess oil goes... I don't know.

Took it back in and made them take out the extra oil and check the codes again because now they read ...

65 Camshaft position sensor

227 O2 Bank 1

228 O2 Bank 2

I am wondering what to do and what to believe at this point... is it likely the extra oil messed up the oxygen sensors?

I need to get to clients but will it hurt my car to drive it long distances?

It had been stalling out before they replaced the camshaft sensor. It's at least not doing that now.

Expert advice would sure be appreciated!

Thanks ! ~ Cheryl

  • Welcome to the site! I'm going to assume this is a late '90's Z3. Were the O2 sensors changed recently?
    – Zaid
    Commented Aug 15, 2015 at 1:51
  • It's a 2001... 44,000 miles. And that place that changed the oil the next day they changed the camshaft sensor. But check engine light came back on so I checked the oil and saw it was almost a quart over... Where did the rest go? Could that mess up my o2 sensors and my new camshaft sensor? Commented Aug 15, 2015 at 1:58
  • Only have had it 10 days and this is all the maintenance I have done. Commented Aug 15, 2015 at 1:59
  • 2
    I was thinking that extra half a quart may have done some damage... Because he put in all the quarts of oil. I watched him. But didn't count them. I asked them to begin with if they were familiar with BMW's and he said yes. Commented Aug 15, 2015 at 2:04

1 Answer 1


Is it likely the extra oil messed up the oxygen sensors?

I don't think so; not in a few days' worth of driving if the O2's were healthy to begin with.

It is true that if engine oil has been overfilled, more of it will make its way to the exhaust where it will encounter the O2 sensors, causing them to foul, but the abuse would have to be over a longer period of time.

One thing worth mentioning is a visual check; there is usually a telltale blue smoke if there is oil mixing in the exhaust. If you can still see blue smoke, this tells me that regardless of oil level you have a bigger problem.

So what could it be then?

In the comments I asked about the age of the O2 sensors, since they will age over time and eventually need replacing.

Perhaps the excess oil was the last straw for them, but they were likely in need of replacement to begin with.

You really should get in touch with the Tampa dealer and ask for the vehicle's service history.

In the absence of service history, you'll have to assume the worst and say that they are 14 years old now, in which case replacing them makes a lot of sense¹.

After replacing them, drive the car for about 200 miles; if the sensors were bad it should feel like a different car.

I need to get to clients but will it hurt my car to drive it long distances?

Not really. The car might feel a little flat but you won't risk damaging the vehicle by driving it for long distances if it is just a matter of bad O2 sensors.

The reason for this is that BMW has designed fallback mechanisms into its vehicles where it assumes certain behavior if it doesn't trust certain sensors like the O2's and the MAF's.

Return of the CPS code

This is hard to judge without hooking the vehicle up to a dedicated scan tool, but one thing to check is whether the VANOS unit has been refreshed recently, as VANOS solenoids jammed with crud may cause this (amongst a whole host of other possibilities).

This isn't something BMW dealerships will do (they usually just replace the whole shebang for big bucks), but reputable independent BMW specialists will know how to perform this.


  1. There is only so much diagnosis possible over the Internet

    The best thing for you to do at this stage is have the vehicle checked by a trusted independent BMW specialist that has access to BMW-specific software for running code scans and tests.

    There are plenty of other possibilities that might explain what you're experiencing; this post is merely my take on the information presented.

  2. Reach out to Z3 gurus

    There will be a wealth of information and resources on the dedicated BMW forums if you present your problem there. However, it can be a challenge to differentiate between useful and not-so-useful information.

  3. Monitor your oil level and continue checking for leaks

    You probably noticed the oil puddle because of a seal or gasket that didn't like the high oil pressure due to overfilling.

Hope this helps and all the best.

¹ - I normally don't advocate replacing parts without running some tests, but if these are the circumstances I think it is a sensible call.

  • Very well post again zaid Commented Aug 28, 2015 at 8:24

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