Subaru oxygen sensor

subaru
forester

#1

i have a 2003 forester with 115,000 miles. i have been having problems with no pick up, and have had oxygen sensor replaced, air and fuel filters replaced and fuel lines flushed with out it fixing the problem. now a new mechanic says the first replaced a standard oxygen sensor when it was supposed to be a wide band sensor. does this matter and could it be the problem?


#2

Yes, it matters. And often with parts like O2 sensors it pays to stick with OEM (from Subaru) parts. It also pays to first do testing before blindly changing parts.

Did the check engine light (CEL) come on? O2 sensors will trip the light and generally not cause driveability problems. Your old sensor was probably just fine.

With no CEL I would inspect the spark plugs, test for a strong spark, test for a restriction in the exhaust system and do a compression test.


#3

yes, the cel has come on, repeatedly. they did change the spark plugs, i’m not aware of what a compression test is or if it was done. so, if the wrong type of sensor is put in, it still shouldn’t change driveability?


#4

Since the cel came on there are error codes stored on the engine computer. Have them read and post them here. They look like P0123 etc.


#5

I agree with having the car scanned for codes (AutoZone, etc. will do it free).
If the car appears to run evenly but is simply sluggish then you might consider one of the following:
Weak fuel pressure.
Clogged catalytic converter.
Slipping clutch if a manual transmission.
Slipping clutch packs if an automatic transmission.

I hate to hear things like fuel lines being flushed because this starts falling into the wild guessing category.