Hi Guys,

I got a P0411 a while ago and it was the notorious combi-valve hose.

That was late last year. It was the only DTC I've ever had with this car. I haven't had any issues since then..........until now.

Between then and now - as preventive maintenance only - I've replaced all vacuum hoses, vacuum check valves (yes they're facing the right direction). I've seafoamed, installed a high flow drop in air filter and stainless muffler, fuel filter, spark plugs, vacuum/boost gauge, crankshaft positioning sensor and cleaned the throttle body (with carb cleaner) and the MAF (with MAF cleaner).

Everything is tip top, but apparently not, because the car is now consistently throwing the following codes:

Faults Found:
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-00 - -
17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 35-10 - Please Register/Activate - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16685 - Cylinder 1 Misfire Detected
P0301 - 35-10 - Please Register/Activate - Intermittent
16687 - Cylinder 3 Misfire Detected
P0303 - 35-10 - Please Register/Activate - Intermittent
16688 - Cylinder 4: Misfire Detected
P0304 - 35-10 - - - Intermittent
16825 - EVAP Emission Control Sys: Incorrect Flow
P0441 - 35-10 - Please Register/Activate - Intermittent
16686 - Cylinder 2 Misfire Detected
P0302 - 35-10 - Please Register/Activate - Intermittent


I know I don't have a vacuum leak.

I just checked the purge valve and it seems fine (I can't blow through it).

I have a new fuel filter.

I have a new FPR vacuum hose.

There is obviously a common thread here. I just can't figure it out.

I'm out of ideas. Can anyone help please?

Thanks in advance!

 

When did all these codes pop up? What did you do right before it went crazy like this?

 

it was sometime between replacing that stupid 3-way EGR hose, Seafoaming, or when I replaced the check valves (which are all facing in the proper direction).

I also did the speed sensor around the same time.

 

First and foremost make sure all the vacuum lines are routed properly. Did you seafoam the intake mani? I did that a few times till it led to my Bank 2, Secondary 02 sensor to fail. It is better to seafoam the intake before you put the new parts on, at least from my experience.

 

I Seafoamed before and after (I believe). First using the brake booster line (before the check valves) and again, using one of the vacuum hoses by the manifold (I can't remember which).

The Vacuum hoses are 100%. I'm not worried about those - their new and proper. The check valves are new and proper. The purge valve seems fine. Plugs looked good. Boost gauge is reading perfect vacuum when driving and I have a new fuel filter.

I reset everything and so far so good. If it throws the same codes again, I'm going to try new (different) plugs and maybe coil packs/wires. Otherwise I'm looking at ECU problems.

We'll see. Thanks for your input!