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Registered
2003 Forester XT
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500 Posts
Discussion Starter #1
Tried to reset my ecu last night to see if I could get this new maf sensor to work. Left the battery disconnected for about 2 hours. I had unplugged the old maf with the ignition on as to throw up an error code to see if that would also clear.

Once I started it I still had the error code and left it running for about 10 minutes it was pretty rough and the revs kept dropping and rising. Though it was just adjusting to the new maf. Anyhoo, switched off the engine and it just stalled right away again, put the old one back in and it was fine again
Had I reset the ecu? Also should I just wait for the engine to warm up and drive off without switching it off?
Will 5 hours be long enough to reset the ecu? I have disconnected the batt and swapped the new maf back in. Will try during lunch or wait till after work which will be over 8 hours.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,732 Posts
Usually the ECU is reset within 15-20 minutes of killing the power. If you reset the ECU, plugged in the new MAF and it doesn't work properly, but the old ones does, you have a faulty MAF. Is it Genuine Subaru part, or aftermarket?
 

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Registered
2003 Forester XT
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500 Posts
Discussion Starter #3
It's an aftermarket. But they are going to replace it as it has a years warranty. Guy said he had not had many problems with them so far, but faulty ones do get through. Ho hum. I will give it a try at lunch and see what happens.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
Joined
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5,732 Posts
^^ I've heard nothing but horror stories from people who go with aftermarket MAF instead of using Genuine Subaru ones. The MAF is one of the most important sensors on the car, I would seriously consider buying a Genuine one if the next one doesn't work out right.
 

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Don, King of the parts diagram
MY11 WRX STi Sedan 6MT
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5,870 Posts
Tried to reset my ecu last night to see if I could get this new maf sensor to work. Left the battery disconnected for about 2 hours. I had unplugged the old maf with the ignition on as to throw up an error code to see if that would also clear.

Once I started it I still had the error code and left it running for about 10 minutes it was pretty rough and the revs kept dropping and rising. Though it was just adjusting to the new maf. Anyhoo, switched off the engine and it just stalled right away again, put the old one back in and it was fine again
Had I reset the ecu? Also should I just wait for the engine to warm up and drive off without switching it off?
Will 5 hours be long enough to reset the ecu? I have disconnected the batt and swapped the new maf back in. Will try during lunch or wait till after work which will be over 8 hours.

Adamh,
As yours is a newage denso ECU you can't clear the fault codes just by disconnecting the battery, you need to use a code reader to reset it.

Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / ECU Reset
 

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Registered
2016 Outback and WRX CVT
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2,551 Posts
After the battery has been disconnected, pump the brakes until your tail-lights no longer light up to discharge any residual energy in the charging system.

No matter how long you leave the car "unplugged" with the battery cable(s) off, there remains the possibility that something is managing to store enough energy - so you've gotta purge that, first. :wink:

But like don1952 said, there are codes which cannot be eradicated fully via a simple "disconnect the wires" reset.
 

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Registered
2003 Forester XT
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500 Posts
Discussion Starter #7
I had left ot for 5 hours and turned the ignition and pumped the breaks to make sure. Started ok and left it to warm up for 5 min with rear heater and air con on, then went for a drive. Was ok until I got back ans switched it off. Wouldn't start, just kept stalling straight away. Stuck old one back in and was fine again. Sent it back so waiting for a replacement.
 
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