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senikc 12-28-2012 10:11 PM

Service engine soon light
Old subject which seems to be a constant problem with Z3
1999 Z3 2.5 Liter. Peake code reader E3 & E4 O2 sensor adaptation limit cyl 1-3 & 4-6
Have changed, CCV Valve and hoses, O2 pre cat sensors, fuel filter, done a leak test on hoses, no leaks evident.
Could it be the fuel tank emissions, charcoal canisiter, vent lines?

Any suggestions what to check next?

FZbar 12-29-2012 06:31 AM

A repeated problem with my 2002 Z3 2.5 liter was the exhaust camshaft position sensor. It happened three times.

It could be related to an oxygen sensor error.

Good luck.

Blacklane 12-29-2012 05:15 PM

I was thinking Mass Airflow Sensor. An unknown reading from that would cause mixture problems, but normally, you would expect a few other codes for this condition, such as P0170 Fuel Trim.
I have also heard of the post-cat O2 sensor causing pre-cat O2 sensor tests to fail, but normally the efficiency tests, not the limit tests.
I did a quick forum search on "E3" and came up with dozens of hits. Maybe you should look over those, as well as "E4."
It might be worth the expense to have more diagnostics done. A well-equipped shop could tell you the oxygen levels in the exhaust, read the various sensor levels, and quickly eliminate a lot of unknowns.

morrieschoice 12-29-2012 05:59 PM

MAF Sensor
I got same codes on my car...thought it was the MAF sensor...bought one & same codes still came up. I did NOT check the boots (there are 2 of them) connected to sensor from engine side...found a tear in the boot connected to the sensor. Now I have a new "in box" MAF sensor f/sale...:)

senikc 12-30-2012 07:59 PM

Thanks for the information and suggestions, I will post results when and if I resolve the problem.

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