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Code PO170 Fuel Trim Malfunction Bank 1 on '99 ej22
Posted 25 May 2005 - 11:15 AM
Posted 26 May 2005 - 09:54 PM
The light will go off by itself usually, but the code should not disappear from the memory without it being manually cleared or a loss of power.
Posted 27 May 2005 - 12:23 PM
Posted 28 May 2005 - 06:29 AM
Posted 28 May 2005 - 07:11 AM
It would be helpful to read the fuel trim using a scanner to see which direction the ECU has adjusted it. If it's adjusted rich (perceived lean condition) it might be caused by an air leak somewhere. When was the last time the fuel filter was changed? Oh, I see, no service history. Plugged fuel filter would cause a uniform fuel delivery problem. If the trim is set lean (perceived rich condition) I would suspect air filter or a faulty sensor(s) or injector(s).
I would start with a fuel filter, air filter, run a couple tanks of Techron, and check for air and vacuum leaks. If that doesn't work I would start thinking about the sensors. I would try these inexpensive things first, as they are necessary regardless due to not having a service history. If that doesn't work you may need a tech that has a scanner.
Posted 28 May 2005 - 09:23 AM
Posted 31 May 2005 - 08:47 PM
Posted 02 April 2013 - 12:07 AM
RE: PO 170 Code, in our 1997 Subaru Legacy Outback.
We had the PO 170 code show up 5 times in a row! First, we replaced the O2 sensor. Code came back. Faulty sensor, replaced it. Code came back on.
Cleaned MAS (Mass Air Sensor) and replaced air filter, it was filthy. Code came back again! Finally went to Subaru Recycled Parts yard, got a used
Mass Air Sensor for $45, just drove the car home over 100 miles and no code!! Yay! Also, we got some other codes in between all this, which were due to hoses that had come off, so do check all hoses as well for vacuum leaks.
Edited by ferp420, 02 April 2013 - 12:09 AM.
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