1995SubaruImpreza Posted April 25, 2008 Share Posted April 25, 2008 So I have had my 01 Forester check engine light going off and on for a while now, each time I had it checked I was told it was nothing more than likely a loose fuel cap. The check engine light has been more persistant lately, rarely going out and there has been a rattle noise for about 2 month when i start up the car that seems to go away once the car has warmed up. I was thinking maybe a heat shield or something...nope turns out that is the sound of my bank account draining, I had it hooked up to a code reader again today... 0420... I know this is the expensive code, but can anyone tell me what I should be expecting cost wise??? And is there anyhting I can do in the meantime maybe a temp repair, I just bought I house this week so the funds are kind of short... Quote Link to comment Share on other sites More sharing options...
nipper Posted April 25, 2008 Share Posted April 25, 2008 Its not an expensive code unless you blindly listen to a mechanic. How many miles on the car. This is classic front O2 sensor being tired, or finally dying. Even IF it is a cat, this still has to be replaced, so replace it first with an OE sensor and see what happens. And yes that rattling may still be a heat shield, easy to fix. It may be a cat too, but i doubt it. When the car is cold hit the cat with your hand. If it doesnt rattle its fine. nipper Quote Link to comment Share on other sites More sharing options...
OB99W Posted April 25, 2008 Share Posted April 25, 2008 [...]there has been a rattle noise for about 2 month when i start up the car that seems to go away once the car has warmed up. I was thinking maybe a heat shield or something...nope turns out that is the sound of my bank account drainingThe noise might still be due to a loose heat shield, or other not-too-significant cause. I had it hooked up to a code reader again today... 0420... I know this is the expensive code[...]DTC P0420 isn't always expensive to resolve. While it's the code indicating a catalyst efficiency problem, it doesn't always mean the cat's the culprit. Quite frequently, a failing front O2 sensor is the cause, and replacement with an OEM one solves the problem. EDIT: Nipper posted while I typed. At least we both said about the same thing. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 25, 2008 Share Posted April 25, 2008 replace the front O2 sensor. they're about $100 from subaru (i just bought 3 of them). very easy to replace, just need a...22 or 24 mm wrench and that's it. get this part from Subaru. i think you can gather this from the two very competent people that just replied, but subaru catalytic converter failure is rare...even many 80's subaru's out there at 20 years old are still running their original converter (well...not counting the ones lost to rust!). these codes only tell you what the ECU is 'seeing', they don't tell you what is wrong directly and you still need to understand and read them. so "catalyst" whatever does not mean the catalytic converter is bad. there is no "catalytic converter" sensor, so there's really no way for the ECU to know it's bad, it would have to be inferred by the person looking at it. it means it "could" be bad, but there's a number of things it could be and the actual converter is a very low percentage chance. Quote Link to comment Share on other sites More sharing options...
1995SubaruImpreza Posted April 25, 2008 Author Share Posted April 25, 2008 Its not an expensive code unless you blindly listen to a mechanic. How many miles on the car. nipper it has 235000kms on it, ummm about 146022miles I think. Quote Link to comment Share on other sites More sharing options...
nipper Posted April 25, 2008 Share Posted April 25, 2008 it has 235000kms on it, ummm about 146022miles I think. Yup your due for an O2 sensor. Might as well get a pcv valve too, bet that hasnt been changed. nipper Quote Link to comment Share on other sites More sharing options...
1995SubaruImpreza Posted April 25, 2008 Author Share Posted April 25, 2008 Yup your due for an O2 sensor. Might as well get a pcv valve too, bet that hasnt been changed. nipper I will try that first and have the heat shield check out to see if that is what is rattling, do I chane both O2 sensors (front with OEM and rear with either right?) or just the front one? Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 25, 2008 Share Posted April 25, 2008 just the front. i just replaced mine at 120,000 as preventative maintenance and all said replacing the rear was pointless unless i got a CEL. so i didn't replace it on their recommendations. Quote Link to comment Share on other sites More sharing options...
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