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2003 Baja H4 EJ25 - heads rebuilt and new short block 10/14 -- AND 2004 35th Anniversary Edition OB H6
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Discussion Starter #1
So, I've got the "rattle" that certainly "sounds like" the first CAT is toast on my 2003 Baja 2.5... I used my "mechanics stethoscope" and tapping on cat with a pipe I can induce the sound... BUT, I'm not getting the P0420 code...? What I'm getting is: 0303 & 0304 (misfires) and 0030 (bank 1 sensor 1 control circuit) and 0032 (over heat o2 sensor)... -- All just a prequel to 0420? - or what??
 

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2003 Baja H4 EJ25 - heads rebuilt and new short block 10/14 -- AND 2004 35th Anniversary Edition OB H6
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Discussion Starter #2
- someone? - anyone? start with the CAt or with the O2 sensors? thoughts?
 

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2009 Outback H-4
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I have replaced two cats in the last 26K miles on my 09 Outback. Never threw a code! The symptom was lack of power.
 

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2003 Baja H4 EJ25 - heads rebuilt and new short block 10/14 -- AND 2004 35th Anniversary Edition OB H6
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Discussion Starter #4
I have replaced two cats in the last 26K miles on my 09 Outback. Never threw a code! The symptom was lack of power.
Hmmm - Did you use OEM Cat or after market?
 

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So, I've got the "rattle" that certainly "sounds like" the first CAT is toast on my 2003 Baja 2.5... I used my "mechanics stethoscope" and tapping on cat with a pipe I can induce the sound... BUT, I'm not getting the P0420 code...? What I'm getting is: 0303 & 0304 (misfires) and 0030 (bank 1 sensor 1 control circuit) and 0032 (over heat o2 sensor)... -- All just a prequel to 0420? - or what??
- someone? - anyone? start with the CAt or with the O2 sensors? thoughts?
How long have you been driving with the P0030 and P0032 codes?

With those codes, the A/F sensor is probably not working and the fuel control remains in Open Loop, which could mean the engine is running on the rich side. Excess fuel can damage the cat over time. Misfires are also a source of excess fuel that can cause the cat to overheat and fail. All to say, first deal with P0030 and P0032 codes. The sensor itself might be bad, or there's a problem in the heater control, wiring between sensor and ECM, or the ECM itself. The cat might have to be replaced, but there's no point putting in a new one with the engine not running properly.
 

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2003 Baja H4 EJ25 - heads rebuilt and new short block 10/14 -- AND 2004 35th Anniversary Edition OB H6
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157 Posts
Discussion Starter #6
How long have you been driving with the P0030 and P0032 codes?

With those codes, the A/F sensor is probably not working and the fuel control remains in Open Loop, which could mean the engine is running on the rich side. Excess fuel can damage the cat over time. Misfires are also a source of excess fuel that can cause the cat to overheat and fail. All to say, first deal with P0030 and P0032 codes. The sensor itself might be bad, or there's a problem in the heater control, wiring between sensor and ECM, or the ECM itself. The cat might have to be replaced, but there's no point putting in a new one with the engine not running properly.
Thanks! - That's how we'll approach it then.
 

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2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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the po420 is mild and caused by whatever conditions are making the other codes.

advice: don't change a perfectly good cat at this point.

miles on this?

I have one newer front o2 sensor on my 2.5 car,...the rear has been replaced 2x (due to p0420 blues). 113,000 miles presently.


front o2 sensor controls the whole car with its data,...or its poor data. (and can make for misfires).

alternatively: what do you got for a coil, plugs and plug wires. (hopefully a subaru coil, and NGK plugs/ wires).
 

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Discussion Starter #9
the po420 is mild and caused by whatever conditions are making the other codes.

advice: don't change a perfectly good cat at this point.

miles on this?

I have one newer front o2 sensor on my 2.5 car,...the rear has been replaced 2x (due to p0420 blues). 113,000 miles presently.


front o2 sensor controls the whole car with its data,...or its poor data. (and can make for misfires).

alternatively: what do you got for a coil, plugs and plug wires. (hopefully a subaru coil, and NGK plugs/ wires).
I'll look into what parts are in there over the next few days - hard to say about the miles... - not much on the engine, I bought a short block and rebuilt. The rest of the car has more like 160,000 on it maybe (?) but, then again, I don't know how old the exhaust system is. I've had it between 3 - 4 years. --

I'll report back here. As far as the CAT goes, should I be fairly certain that the one that "rattles" (front) is shot?? --- IF I do get to replacing one or both, would you expect problems with an after-market high flow brand? - or should I stick with OEM?
 

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Lawn ornament XT
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I'll look into what parts are in there over the next few days - hard to say about the miles... - not much on the engine, I bought a short block and rebuilt. The rest of the car has more like 160,000 on it maybe (?) but, then again, I don't know how old the exhaust system is. I've had it between 3 - 4 years. --

I'll report back here. As far as the CAT goes, should I be fairly certain that the one that "rattles" (front) is shot?? --- IF I do get to replacing one or both, would you expect problems with an after-market high flow brand? - or should I stick with OEM?
Rattles mean nothing. The heat shields always rattle on one part of the exhaust or another.

The only way to know if the cat is any good is to run through the diagnostics- look at the measurements coming back from the O2 sensors and you'll see if the converters are working correctly.
 

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2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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I'll look into what parts are in there over the next few days - hard to say about the miles... - not much on the engine, I bought a short block and rebuilt. The rest of the car has more like 160,000 on it maybe (?) but, then again, I don't know how old the exhaust system is. I've had it between 3 - 4 years. --

I'll report back here. As far as the CAT goes, should I be fairly certain that the one that "rattles" (front) is shot?? --- IF I do get to replacing one or both, would you expect problems with an after-market high flow brand? - or should I stick with OEM?
if by rattles you mean that the exhaust is open to the outside air,...this lets it suck in some extra air from the outside,...and if that is comming in before the rear o2 sensor,...you get a p0420 easy. = "too much oxygen" vs. how much is "supposed" to be in a plumbed up exhaust system..
 

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Discussion Starter #12
Riddle me this?!!

So, I started out with the occasional misfires on 3 & 4, the 0032 and the 0030 and the rattle.

I got a new (Walker) CAT and two cheap sensors off amazon.

I started getting 0032 & 0037. Cleared a few times and came back immediately.

- figured it had to be the cheap sensors so I ordered a new A/F sensor (pricier Densi)

- while I wait for that to arrive, I thought, "Hey - I'll replace the O2 sensor after the CAT with the old one from the old cat and see what happens.

- I switch 'em and drive on over to the parts store to clear the codes and check it out.

- unsurprisingly, when I got there, I had the 0032 & 0037 to clear - PLUS the return of the 0030 (pending).

- I cleared 'em - expecting to take a 10 minute drive and have them all return.

I've taken 6 or 8 ten minute drives today now and ZERO codes! ?? wth?!

Doe that make ANY sense to ANYbody??
 
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