Hello, I have the B230 turbo engine with 415 000 km on it.
The timing spec says -12 deg TDC and mine is about -20.
I have flunked badly on the NO2 part of the emissions test and advanced timing is one of the potential causes.

The car runs pretty well, although has some blowby.

The timing belt is in good shape and the cam and crankshaft marks are in line.
No engine fault codes.
Idle is steady although a bit high at 1000 rpm but I see no signs of intake leak.

O2 sensor is new and tested well on voltmeter.
Spark plugs and wires are new.

Any ideas of reasons for the advanced timing and how to fix??

Thanks.