check engine light on -- but communications fails

[zyewdall]

So... I plugged in the code reader and it said communication failed... it could be a bad code reader (Cheapo $89 unit from Crutchfield, I don't have any other vehicles new enough to test it on). Or, is there something else I need to do to get the car to communicate with the code reader? Something to activate it?

 

1997 Impreza Outback Sport 2.2

[i_subie]

Did you turn the key to the "ON" position?

[zyewdall]

Yeah, the engine is running. And I tried stopping it and restarting it and no change...

[i_subie]

The car/engine isn't suppose to be running while you are checking for codes.

[nipper]

Go to an autoparts store that reads codes for free and see if it works for them.

 

nipper

[cagranitz]

I seems some code readers are unable to communicate with some Subaru models. I bought one of the CanOBD readers from Walmart. On my 2001 Outback it would work just fine. On my wifes 2000 Outback it would fail to communicate no matter what I did. I contacted CanOBD and they sent me a different model reader which worked fine with the 2000 OBW. It also works with the 2001.

[Cougar]

The newer Subarus use the Canbus protocol but I think the pre 2001 models use ISO-9141. You need to make sure the reader can support that.

[zyewdall]

Borrowed the fancy reader from Checker Auto and it read it... ISO9141 indeed. Though the one I bought claims to do that...

 

Anyway, PO141 -- second heater bank is the code... guy in the store says that's the rear O2 sensor. I got a generic replacement for it, as well as new plugs, wires and air filter (have no idea how old those are, and my experience is that no one every remembers to change them....). Car's getting about 23mpg

[nipper]

Go with OE wires. Replace the PCV valve.

 

It is winter, thats about right.

 

Last night here in NY it was 14 degrees with a 40 mph winf. On the scan gauge I could watch the mpg go down to 14 when the wind hit Blu. I get about 20 in bitter cold, as low as 16 if it is all short trips (1 mile or less).

 

 

You may be @ 23, but if it was anything else it would be 16.

 

 

nipper

[Cougar]

The info about the sensor location is correct.

 

As far as a good reader/scanner goes, I like and use the Equus model 3130 by Innova. There are other good brands also available, like Actron. You can get them at Ebay for a good price if you want to go that route.

[zyewdall]

You may be @ 23, but if it was anything else it would be 16.

nipper

 

Yeah, it's still way better than all the toyota pickups that are the other main choice of vehicle other than subaru's here, I admit. But my old '89 GL usually still averaged around 26 in the winter and 29 in summer, unless there was alot of snowdrift bashing going on. Even the '90 legacy seemed to average about 26 in the same type of driving as the impreza's 23.

 

Someone really jacked up the O2 sensors on the Imp... the front sensor, for some reason, had a big extension plugged in in line, instead of just going directly from the sensor to the harness, and the wire from the back O2 sensor to the harness is missing entirely... looks like it was violently chewed off the sensor, and who knows where the other end went... I think I can make a new wire for the new sensor using the silly extension that was on the front one though And, it already runs better with the new plugs and air filter (air filter was absolutely filthy, and plugs were quite worn...)