Replacing front exhaust manifold / catalytic converter on 2005 E46 325xiT

[agreatham]

Okay, I'm going from oil changes to something more substantial. I have an 05 325xiT with 175k miles on it and last week the "Service Engine Soon" light went on. Got a Peake R5/FCX(3) scan tool and it's reporting 19 E9 8D. Table 19 code E9 is "Catalyst efficiency below threshold, Cyl #1-3". Put my hand over the exhaust pipes and there's air pressure coming out of the left pipe but not the right. I took it to Curry's and they confirmed that the front manifold/cat needs to be replaced. Using BMW parts and 8 hrs of labor would run me $3k so I opted to do it myself with the help of a Bentley manual and parts from BavAuto ($600). Parts are coming in this week and I'm also ordering an engine lifting tool. Is there anything that's not in the manual that I should be looking out for? It seems like a straightforward plumbing job.

Also, anybody know what the 8D code is? It's not in the Peake manual.

Thanks.

[Nick325xiT 5spd]

It can be a pain in the ass to get those off while the engine is in the car. The studs will probably come out of the head (expect to replace), and it's a fairly cramped area, so you may need to be creative to get the thing out. In addition to lifting the engine, be prepared to pull off the engine mount arm and/or move the a/c compressor (you can unbolt it and shift it around without depressurizing).

Be aware that there is a valve in the tailpipe (iirc the right one, but it's been many years) that closes the tip under light load. No exhaust flow at the tip does not mean that the cat is blocked, or that there's an issue with the cat.

I'd consider replacing the post-cat O2 sensor before doing anything else. If you do the whole thing, you should replace that anyway, so you lose nothing.

[JC5]

All that plus new gasket and copper, 1 time use, exhaust nuts.

Soak all the bolts/ nuts in penetrating oil.

If any of the studs come out, put them back in finger tight ONLY. No torque spec. You can damage the aluminum head by trying to force them in. The bolts do have a torque spec though.

Be prepared to get fusratated. In the end it looks like you'll save a ton of money.

[agreatham]

Did not know that about the valve in the tailpipe. I'll change out the oxygen sensor, clear the code and see if it that fixes it. Stay tuned.

[agreatham]

Sorry for the late update. I tried for a week to get the post-cat lambda sensor off of bank 1 but with 174k of heat cycles, it just wasn't going anywhere. So I took the car to Curry's in Gainesville with the parts from BavAuto in the trunk and they changed the manifold, gasket, pre- and post-cat sensors, bolts and heat shield for about $900.00. So far so good but now the smog pump is dead so I need to replace that, and check the valve and the vacuum hoses. I've certainly learned a lot about emission systems in the past couple of months.