Fresh Out of Outbacks!
Don't assume the cats have failed. The error message just means the car can't tell if they are working right, so it may be just a sensor or yet another problem. Find and read cardoc's P0420 diagnostics thread before spending money.My 99 subaru outback was rear ended causing bumper, body and frame damage (still driveable). A few days later the CEL came on and shows P0420 Catalyst System Efficiency Below Threshold. There's no obvious external damage to the converters. My question is could the impact have caused the cat failure and therefore be added to the damage claim? What evidence might confirm this? I'm the second owner and have receipts that show the original converters (front and rear) were replaced under warranty at 25,000 miles in 2001. The car now has only 68000 miles. Shouldn't they have lasted much longer? Thanks for any guidance.
A rear end hit can include the tailpipe and muffler, and when they get shoved out of the way in a collision the stress can be transferred forwards through the mid pipe to the cats and sensors near the front. So whatever the problem actually is, yes there is a chance it is related to the hit.
It could be as simple as an air leak in the exhaust near the front, and the leak could well be from the hit.