9 replies to this topic

[Msk]

Hi I have an 2003 forester. An orange engine light came on and stayed on. The mechanic said it was an o2 sensor and was because I was running 91 fuel and that I should be running 98 fuel. Has anyone else had this problem or heard of this.

[Beckers]

Is your car a turbo ??

[Msk]

No standdsard 2.5l
Sorry. No normal 2.5l

[El_Freddo]

91RON will be just fine in your Foz. My sister has a 2.5L Liberty (2000) and that’s all it’s given to eat.

Have you read the codes to see what the issue relates to? It could be more than the O2 sensor. And it’s unusual in my experience for the O2 sensor to throw a code, they usually die just enough no to throw a code...

Cheers

Bennie

[Niko]

95/98 every 3rd to 4th tank can help. But 91 should be fine.

[Ads]

...and was because I was running 91 fuel...

 

Do you mean regular 91ULP or do you mean E10? If E10, I can understand the mechanic mentioning the possible link even if it is unlikely..

 

Apart from the check engine light, has the car been running strange/rough?

What is happening now? Did the mechanic replace the sensor and/or just tell you to run 98 from now on?

[Msk]

91ulp.cars running normal. Light came back on 100m after having it reset. Didn't replace sensor, mechanic said they were about $500 bucks which I don't have. He said he has had the same problem on numerous subys.

[Barbbachello]

Yeah running 91 is perfectly fine. Thats what theyre rated for from subaru. They do wear out over time but not from running 91 fuel in a 91 fuel car

Id be finding a new mechanic if he thinks thats the cause

[RX25SE]

I wish I had a dollar every time someone replaced an O2 sensor because of a code.....

Check for intake and exhaust leaks for a start.

Knowing what O2 code had logged would also be a big help.

[NQRSoobee]

$500 for an O2 sensor!!!!!  Oh my #$%&.  That's such rip off of a price.  When I had my old Gen2 RX I bought an O2 sensor off of eBay for $70 then had my mobile mechanic fit it as part of the normal service for the car which cost me something like an extra $40.

 

During hot weather that old car would run fine, no codes all good... but in cold weather floor it & it'd still throw an O2 code.

 

To check codes plug the two, I think, is it green plugs together under the dash & read the code from the blinking CEL with ignition on but engine not running then work it out from there.  Don't forget to unplug the plugs after reading off all the codes; long blink for tens, short blink for ones.  From the brains trust on this group & a bit of searching of both Partsouq.com should be able to identify what's going on plus perhaps eBay for a reasonably cheap fix.

 

A good few on here recommend cleaning the IACV (Idle Air Control Valve) as they can get a bit sticky after quite a bit of use.  A lot on here will use Subaru's UEC (Upper Engine Cleaner) which is sprayed into the intake just after the engine side of the air cleaner to clean the muck out of the engine including the IACV.  I didn't have UEC so I carefully pulled each item all apart & did all the cleaning myself.

 

Per the other advice check vacuum hoses as they can get a bit brittle, crack & perish with age so letting in air & throwing an O2 code.

 

Good luck.