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mtfraker

cel 0420, pinging, poor fuel economy

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I am new at posting threads, so bear with me.

 

In March 2004, I purchased a used 2000 Subaru Outback Wagon Limited with 117K miles. Several weeks later the check engine light appeared. I've diagnosed it as P0420 - Catalyst System Efficiency Below Threshold (Bank 1). Also, the car pings quite loudly, especially when climbing an incline and running low RPM's. When I use Amoco or Exxon 93 octane, the pinging subsides (a bit but not totally), but when I go back to Amoco or Exxon 87 octane, the pinging returns. Last week at 121K miles, I reset the CEL and changed the spark plugs with NGK BKR6E-11 gapped at .044 as directed. I left the battery cable off for a couple of hours to reset the ECM settings. The next morning, I filled up with Amoco 87 octane. All was well until about 100 miles into that tank of gas. (On two prior occasions, I reset the CEL and it did not come on for about 100 miles.) The CEL is back on and pinging is more prevalent. Also, my fuel economy has been between 19.3 mpg and 21.1 mpg. Furthermore, the transmission seems to shift harder from 1st to 2nd than any other gears and it upshifts quickly when the cruise control is set going up a slight incline. If anyone can offer me advice on what I need to investigate from cheapest/easiest first, it would greatly be appreciated. I am to the point where I feel a dealer visit may be required, unless you all can help me! This is my first Subaru and I love the car, however it replaced a 1990 Buick Regal with 230K miles which never showed the CEL. The previous owner admitted to burning cheap, no brand 87 octane. I removed the throttle body and cleaned it well, but to no avail. Thanking you in advance for your help.

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You might want to have your catalytic converter checked out. It sounds like it could be plugged. I'm willing to bet it is that or a vacuum hose is off or leaking. I had that same problem on my old jeep. My fuel economy cut in half and very rough running engine. One of my vacuum hoses needed replacing and it fixed the problem.

 

-Henry

 

 

 

I am new at posting threads, so bear with me.

 

In March 2004, I purchased a used 2000 Subaru Outback Wagon Limited with 117K miles. Several weeks later the check engine light appeared. I've diagnosed it as P0420 - Catalyst System Efficiency Below Threshold (Bank 1). Also, the car pings quite loudly, especially when climbing an incline and running low RPM's. When I use Amoco or Exxon 93 octane, the pinging subsides (a bit but not totally), but when I go back to Amoco or Exxon 87 octane, the pinging returns. Last week at 121K miles, I reset the CEL and changed the spark plugs with NGK BKR6E-11 gapped at .044 as directed. I left the battery cable off for a couple of hours to reset the ECM settings. The next morning, I filled up with Amoco 87 octane. All was well until about 100 miles into that tank of gas. (On two prior occasions, I reset the CEL and it did not come on for about 100 miles.) The CEL is back on and pinging is more prevalent. Also, my fuel economy has been between 19.3 mpg and 21.1 mpg. Furthermore, the transmission seems to shift harder from 1st to 2nd than any other gears and it upshifts quickly when the cruise control is set going up a slight incline. If anyone can offer me advice on what I need to investigate from cheapest/easiest first, it would greatly be appreciated. I am to the point where I feel a dealer visit may be required, unless you all can help me! This is my first Subaru and I love the car, however it replaced a 1990 Buick Regal with 230K miles which never showed the CEL. The previous owner admitted to burning cheap, no brand 87 octane. I removed the throttle body and cleaned it well, but to no avail. Thanking you in advance for your help.

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Another possibility that comes to mind would be a contaminated/lazy front O2 sensor. Might wanna see if there's a service record on whether the sensor's ever been changed. A lazy sensor's gonna result in a richer-than-normal average fuel mixture (poor fuel mileage) but leaner than optimal part-throttle acceleration mixture (spark-knock/downshifting). It's also gonna reduce the crossing count of the front sensor relative to the rear sensor (crossing ratio) and trigger a cat-efficiency code.

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Go to search "catalyst" and look for the thread. This P0420 is very common and there is a lot of chat about it. This happened to me last week. My cel came on after I changed a mucked up air filter. I thought I was in for a new cat. Someone suggested a clogged fuel filter could set off this code due to a poor fuel air ratio. I replaced the fuel filter. I also checked the gaskets to my front cat at both ends. They were a bit corroded and possibly leaking but not noticeably so I sealed the area with exhaust cement.They were correct. Problem solved. As far as going from a GM product to a Subie, cel will go on in Subie for almost nothing and won't go on for a serious problem in GM crap.

I am new at posting threads, so bear with me.

 

In March 2004, I purchased a used 2000 Subaru Outback Wagon Limited with 117K miles. Several weeks later the check engine light appeared. I've diagnosed it as P0420 - Catalyst System Efficiency Below Threshold (Bank 1). Also, the car pings quite loudly, especially when climbing an incline and running low RPM's. When I use Amoco or Exxon 93 octane, the pinging subsides (a bit but not totally), but when I go back to Amoco or Exxon 87 octane, the pinging returns. Last week at 121K miles, I reset the CEL and changed the spark plugs with NGK BKR6E-11 gapped at .044 as directed. I left the battery cable off for a couple of hours to reset the ECM settings. The next morning, I filled up with Amoco 87 octane. All was well until about 100 miles into that tank of gas. (On two prior occasions, I reset the CEL and it did not come on for about 100 miles.) The CEL is back on and pinging is more prevalent. Also, my fuel economy has been between 19.3 mpg and 21.1 mpg. Furthermore, the transmission seems to shift harder from 1st to 2nd than any other gears and it upshifts quickly when the cruise control is set going up a slight incline. If anyone can offer me advice on what I need to investigate from cheapest/easiest first, it would greatly be appreciated. I am to the point where I feel a dealer visit may be required, unless you all can help me! This is my first Subaru and I love the car, however it replaced a 1990 Buick Regal with 230K miles which never showed the CEL. The previous owner admitted to burning cheap, no brand 87 octane. I removed the throttle body and cleaned it well, but to no avail. Thanking you in advance for your help.

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