I'm looking for the experience of those that have been down this road before.

I am the second owner of an 07 turbo with a bit over 30k miles. The car has modified suspension, but no engine mods and stock tune. I'm getting a P0430 DTC code, converter not working at optimal efficiency on bank 2. I have swapped out both the leading and trailing O2 sensors with new parts, and have no change. The turbo has a broken/missing stud on the upper/inboard connection to the cat, but there is no evidence of leaking.

Where should I go next? Fix the broken stud? New plugs and coils? The car runs beautifully, but the CEL is annoying. All suggestions appreciated.

--Woody

 

Went through this with my 2002 Boxster.

The by the book is if there are any aging O2 sensor codes with the P0430 (or P0420) to replace the indicated sensors and clear the codes and road test the vehicle. If the P0430 (P0420) code comes back replace the converter.

Does the exhaust make any noise?

That is with my car the root cause of the error code was the converter brick was loose. (Years ago a heavy piece of road debris I think struck the converter housing.)

When cold this brick would knock to the point towards the end I though the crank had too much end play. When hot the brick buzzed like a heat shield was loose.

Eventually I got tired of the noise -- and the worry about getting the car through its emissions test -- and I bought a pair of used exhaust manifolds from a local Porsche salvage business and had these installed. Before I put down my money ($450/each and a bargain compared to the cost of new ones) I gave both manifolds a good shake test to ensure the bricks were nice and secure and I treated the manifolds very gently to ensure I didn't knock a brick loose (fracture the I suspect rather fragile mechanism that is used to hold the brick in place).

Before you replace the converter my advise is to fix the broken stud. An exhaust leak can certainly affect converter efficiency or could affect the O2 sensor reading.

Do this and then see if the error comes back. If it doesn't, win. If it does... well, at least you know.

Might add using salvaged converters might be verboten where you live due to state or federal (?) emission laws. There are EPA (and in CA CARB) approved OEM replacement converters but I know nothing about these.

Oh let me add plugs and possibly coils could be due to be changed. Plugs especially can have a short (relatively speaking) service life and coils can degrade and cause problems. But generally the problems are misfires.

The coils on my Boxster are original (and with now over 303K miles) while the plugs have been changed on schedule ever since I have owned the car from new.

My point is you should replace the plugs if they are due on time/miles and the coils if an examination finds the coils are showing signs of aging but I would not expect this to make any difference in the P0430.

What I found made a bit of difference at least in the case of my Boxster was to switch from a discount gasoline to Shell gasoline. But even if this helps it is just a bandaid the real problem is with the converter (or possibly with the exhaust system, a leak).

 

Thanks, Macster. The sensors have been replaced. I haven't notice the typical converter rattle, but the converter could still be the issue. No legal problem buying/using a salvage converter here, but turbo 997s are not abundant here, and I have wondered what the odds are of getting a good converter use for a now-10-year-old car.

Some have suggested plugs and coils, but I am doubtful. The only issue seems to be cat efficiency, as both I and the ECU believe the engine and fuel delivery are fine.

--Woody

 

I was chasing this on my 996 turbo for over 2 years. It started occasionally (so I just cleared the codes). Eventually it got so frequent (every 2 days) that I was considering must be the converters. However, my tech changed plugs and cleaned the throttle body. Code is now gone. I suspect it was the plugs but could be throttle body? I am code free for over a month now. Fingers crossed.

 

And yes I changed the coils, cleaned maf, filters, etc. Nothing fixed the error. I think it probably happens as plugs begin to fail but still work if this makes sense. Or throttle body isn't closing properly and feeding air intake info wrongly to the ecu. Anyway will keep you posted if the code returns. But as I said thus far all good.

 

Thanks Terminator. I'm going to start with the easier stuff first. MAF is new, but the plugs & coils are unknown and possibly original at 30k miles, so refreshing them is probably a good thing no matter what.

 

If you are tuned, changing plugs @ 30K is about the right time. Spark plugs in tuned cars tend to start going off at that mileage. 2 of my coils were cracked when I replaced them (symptoms in addition to the code I've also had was hesitation in wet weather). Changing coils fixed that but didn't fix my code problem.

I would replace plugs first. Then I would clean the throttle body.

Hope your issue is the same. Let us know how you get on.