Join Date: May 2009
Location: east coast
Car: OBW H6 VDC, Tribeca, XT6
Feedback Score: 1 reviews
during the exhaust work - do you know if any of the sensor locations were moved? doubtful - sounds like all the work was around the muffler?
no exhaust leaks?
do not replace your converters - Subaru converters do not fail unless they are abused - most 1980's Subarus still have the original converters and pass emissions. rust gets them, that's about it. but they're so robust compared to aftermarket i simply weld the rusted flanges back on to avoid going with aftermarket or sick $300 - $600 dealer prices.
the best fix is to simply install the $5 spark plug non-foulers on the rear O2 sensor and be done with this gremlin. it's not an actual issue - more like the tolerances for this particular data point are not realistic for real world applications.
the 0420 code doesn't affect engine performance *at all* - that rear sensor isn't even used by the ECU.
you could try to replace all the O2 sensors if you were gung ho to nail it down, i'd simply install the spacer for $5 and 15 minutes and be done with it.
H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6