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2000 Forester
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44 Posts
Discussion Starter #1
The car has been running poorly with a solid CEL, idling rough with A/C on or with slight engine load (like when stopped uphill).

Ran the codes, and got P1133: Manufacturer Control Fuel Air Metering, indicating a defective o2 sensor.

I replaced the sensor today. The car seems to run the same, except it now gives me an occasional flashing CEL.

So did I...
(A) Botch the sensor replacement somehow;
(B) Introduce a new sensor, which is now identifying a prexisting misfire that wasn't being picked up before; or
(C) Something else

Probably unrelated issue, but I'll toss this in here in case it means anything: the rear wiper doesn't work, but occasionally a whirring sound comes from the rear hatch, which I assume is the motor doing something. It was acting up when I first started the car after replacing the sensor.
 

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Administrator
2007 Forester Sports XT 4EAT
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39,829 Posts
I have a couple questions.
  • Did you use a factory/OEM replacement O2 sensor?
  • Did you do or try an ECM reset so everything starts fresh?
I don't think your rear wiper problem is related to this problem.

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2005 Impreza RS Wagon Auto
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3,658 Posts
Your rear wiper can be fixed by disassembling, it is most likely frozen with rust.

As for your flashing cel, that is misfire condition. Try cleaning the contact on the O2 sensor wire of the lead that is on the car. If you didn't buy a direct fit O2 sensor you wasted your money btw, universals usually cause these issues.
 

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2000 Forester
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44 Posts
Discussion Starter #4
I have a couple questions.
  • Did you use a factory/OEM replacement O2 sensor?
  • Did you do or try an ECM reset so everything starts fresh?
I don't think your rear wiper problem is related to this problem.

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
It's a Bosch direct fit sensor. I did the ECM reset this morning so I wouldn't be setting the alarm off in the middle of the night. The CEL turned off, but now it is flashing occasionally.

The car runs exactly the same as before I did the sensor.
 

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2000 Forester
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44 Posts
Discussion Starter #5
Your rear wiper can be fixed by disassembling, it is most likely frozen with rust.

As for your flashing cel, that is misfire condition. Try cleaning the contact on the O2 sensor wire of the lead that is on the car. If you didn't buy a direct fit O2 sensor you wasted your money btw, universals usually cause these issues.
It's a direct fit. Is it possible to determine the source of the misfire? I ran the codes but found none.

Thanks for the info on the wiper. I hope to someday have resolved as much of the critical problems the car has to be able to worry about whether the wiper works or not.
 

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2000 Forester
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Discussion Starter #6
Update!

Okay, after driving around a bit, the CEL came back on solidly with occasional flashing.

I reran the codes and came up with P0303 -- Cylinder Three Misfire.

Looks like I'll be pulling that plug tonight. Anybody have anything else to add to my troubleshooting activities beyond that?
 

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04 Forester X, MT
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1,039 Posts
when was the last time you changed your plugs or wires?

you could try putting in an old plug if you have one, or swapping wires. if they haven't been removed in a long time you could damage them, so be sure you know you can get replacements before starting.

Advance has NGK recommended plugs around here. I always buy wires from the dealer after numerous issues with various aftermarket wire sets over the years.
 

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2000 Forester
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44 Posts
Discussion Starter #8
when was the last time you changed your plugs or wires?

you could try putting in an old plug if you have one, or swapping wires. if they haven't been removed in a long time you could damage them, so be sure you know you can get replacements before starting.

Advance has NGK recommended plugs around here. I always buy wires from the dealer after numerous issues with various aftermarket wire sets over the years.
I just got the car a little bit ago, so I'm not sure. The ignition coil is relatively new, as are the wires. I don't know about the plugs. I have some paperwork to sort through to see what was replaced when.
 

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2007 Forester Sports XT 4EAT
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Check for corrosion on the wiring connector that plugs into the coil pack & the plug wires that plug into the coil pack. If you find any corrosion, clean & coat with dielectric grease. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2000 Forester
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Discussion Starter #10
I pulled the spark plug from the misfiring cylinder and it looked like crap. I replaced it and the car ran well for about 30 seconds, and then went back to its old ways, flashing CEL and all.

I was about to call it a night after messing with the plug wires for a bit when the cylinder three wire shocked the hell out of me. I pulled the intake back out, removed the wires, applied a ton of grease, and put it all back together. Now the car is running better than it has since I've owned it.

Drove it hard and didn't get the CEL flash (though it is still lit up solid).

Going to replace the other plugs shortly and invest in some decent plug wires at the same time.

So we're moving in the right direction. Thanks, everybody, for the help and insight.

(Next up: exhaust issues)
 

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2000 Forester
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Discussion Starter #12

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2000 Forester
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Discussion Starter #15
Di-electric grease is worth its weight indeed, glad you figured it out!

I grease everything possible when getting a new-used car.
Thanks. Proud to have this thing running well again. Almost wrecked the thing in a parking lot today because I'm not used to throttle response backing out.
 

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2005 Impreza RS Wagon Auto
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Thanks. Proud to have this thing running well again. Almost wrecked the thing in a parking lot today because I'm not used to throttle response backing out.
Lol, quite the difference then. The 2.5N/A s still nice n beefy for a 4 banger!
 
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