Engine Light

[dracmarcz]

I've had my 07 3R-B for just over a year now, and had the Engine Light come on three times now.

Each time has been when travelling at around 80 in sixth gear (e.g. highway roadworks) when it's slightly wet. Everything is fine, then the engine light comes on and the cruise light starts flashing. Previously I would have said that the car drives normally with the engine light on, but last night I thought the car drove a little rougher afterwards.

I took it to Subaru last week and they found error code P0420 but couldn't find a fault so they just reset it.

Couple of questions for the forum:
1. Any ideas regarding the cause of the failure? Anything I can check ( a mechanical lamer) myself?
2. Any way of resetting it myself easily?

[zoidberg99]

Cant help you on the error, but im pretty sure you need the plug in computer to clear the errors.

[Robbks]

it's a rear o2 sensor code.
Shows up errors with incorrect AFR's (Air/Fuel Ratios)
either the cat is not working properly or you have a fuelling issue that's causing the car to run incorrectly, or the sensor is just dying

given it happens at highway cruising speeds, (car is running in closed loop fuelling) your front o2 sensors (responsible for closed loop fuelling adjustments) could need attention.
you could have an exhaust leak which is throwing the readings off.

interrogating the ECU with the Subaru Select Monitor should show the cause of teh issue (if the technician has any clue)
but do a quick look for exhaust leaks, intake leaks, etc

[Woodduck]

Hrm. Search through the 3L section for threads by me. I had a similar problem for the 2 and a half years that i owned my 06 3RB. I had it at multiple dealers at least 10 times for this problem and no fix. There is quite a few other 3L that had the same problem, one that was under warranty ended up having the engine replaced as they couldnt find the problem/fix it. Can you hear if its pinging at all?

[team_subaru]

I have been facing this problem for about 4 months now. Been back to the dealers all these times and still no answers. My VVT sensor on the left back is the problem and they have cleaned the sensor countless times.

The other week they swaped the left to right and right to left sensors to hopefully prove that the sensor is the problem, otherwise its other major issues (cam sprocket or valve problem according to the service dept). I am hoping for the sensor problem. Touch wood it hasn't come back on at the moment but I know it will.

[Woodduck]

My dealer came to the conclusion that it was an oil pressure problem but seeing as it wasnt damaging anything there was no point in pulling the engine apart...to me that was a 'piss off we dont know whats wrong so we'll tell you it'll be expensive just so you piss off" haha.

[Monster]

Yeah I have been having this problem for almost 2 years now as well. It came on while I was driving on the highway at around 80km/h as well. The warning light comes and goes, it shows up less frequent than before, so I am just leaving it alone, because the dealers will have no idea anyway while charging you a fortune as well as damaging other parts you don't know.

[fatfrog02]

Check this thread out. Similar problem in 2.5 GTB.

viewtopic.php?f=18&t=4711