Fault code help needed (P2098-P1322-P1577)

B6/7 S4/RS4
#1

Hello fellas! Been fighting a few fault codes for a while now and could use some help in sorting them out. Emissions test coming up in May,need to get readiness squared away. Here are the results of a recent fault code check.

Saturday, 02 March 2013, 11:40:02:58502

VCDS-Lite Version: Release 1.1
Control Module Part Number: 8E0 910 560 C
Component and/or Version: 4.7L V8/5+ JHM.SG 0010
Software Coding: 0007771
Work Shop Code: WSC 08252
VCID: 253D9611ACEF

3 Faults Found:

18530 - Post-Catalyst Oxygen Sensor Correction; Bank 2: Too Lean
P2098 - 002 - Lower Limit Exceeded

17730 - Knock Sensor 3 (G198): Signal too Large
P1322 - 001 - Upper Limit Exceeded - Intermittent

17985 - Right Engine Mount Solenoid Valve (N145): Open Circuit
P1577 - 004 - No Signal/Communication - Intermittent

The O2 sensor fault is pretty persistant,comes back within a day or two once I clear it. The knock sensor fault only pops up occasionally.

Is it safe to assume that the O2 and knock sensor faults are related? (lean condition leading to detonation? when I get on the gas hard I’m pretty sure I can hear some ping) Or do the fault codes simply indicate a faulty sensor? I have already replaced the MAF sensor and I pulled the intake manifold,replaced the gaskets and re-torqued it. A couple years ago I found the IM bolts finger tight but re-torquing did not correct the O2 sensor fault. Perhaps a vac leak somewhere else? I did re-torque and re checked the IM bolts a few times right after initially re-torquing but I have not had a chance to check the IM bolts again recently and I have not had a chance to spray around the engine with carb cleaner to find a vac leak.

Could an exhaust leak cause the O2 sensor faults? My FI exhaust has not stood up well on certain spots of it being exposed to New England winters and all the road salt we use up here.(car is my DD,installed approx 4 years ago) The O2 sensor bungs and the flanges that connect the DPs to the rest of exhaust are heavily rusted(why were these not made from stainless steel like the rest of the exhaust??? ???) and the flex pipes on the DPs are leaking where the braided mesh meets the solid part of the flex pipe,just before the rusty flanges. It’s an audible exhaust leak at the flex pipes(and maybe at the flanges at this point) but the O2 sensor fault was there well before I could hear or knew of the exhaust leaks.

I have VCDS-lite. Should I check the fuel trims or is there anything else I should check through VCDS to help me fix these faults? Please let me know which checks I can do and I’ll happily report back with the results. On the subject of fuel trims; To check fuel trims,use block 032 in “basic settings”? Also,how should the test be done,from idle to full throttle?

As for the engine mount fault,what are the indications of a bad mount? I don’t notice any unusual vibrations from the engine. I think the mounts have some sort of fluid in them,correct? If the mount were bad,would there be signs of a fluid leak.(took a quick look but could see nothing out of the ordinary with the mount) Or again,could this simply be a bad sensor in the mount?

Ok,sorry for the long winded post. Any help here would be greatly appreciated. TIA

#2

Bank 2 is the drivers side. My thought is faulty/clogged injectors. As for the motor mount, if all feels good you can get a resistor to plug in to eliminate the code for now. Eventually it will have to be replaced.

#3

Thanks Speed. Do you know of any specific tests I can do thru VCDS to help diagnose?

#4

You’re welcome. Since knock sensor 3 is showing the issue, it is either cylinder 5 or 6. You can log the blocks that show you the timing retard or the knock sensor voltage (dont remember which those are off the top of my head). That should pinpoint which cylinder is having the issue. I think (don’t quote me on this one) that you can also see fuel injector voltage. That last one may not be of help if the injector just isn’t flowing correctly.

#5

Lean codes check for vac leaks. Get out the carb cleaner and spray around the intake and the pcv system. The exhaust shouldnt be causing any issues but if you have a clogged cat that can cause some serious damage. The motor mount isnt hslping and might be part of thr knocking issue as well.

#6

^ x2. Also check your intake manifold bolts as these were know to come loose/not be properly torqued.

#7

Thanks Chris and Speed.

Yea,will do the carb cleaner routine this weekend and see if I notice any change in RPM. Will also recheck the IM bolts again. I already had the IM come loose(bolts were only finger tight) a couple of years ago. Replaced the gaskets,re torqued,etc. Maybe they came loose again. Only thing is,the lean fault did not go away after re torquing the IM,but I will check again. Maybe a vac leak somewhere else I guess.

Shouldn’t a lean condition be picked up by the primary O2 sensors? I thought the secondary O2 sensors are for catalytic efficiency and don’t have an effect on A/F ratio and wouldn’t be able to detect a lean condition. (please correct me if I’m wrong. I’m probably way off base with this) Or am I misreading the fault scan results. The “post catalyst oxygen sensors” are the one’s farthest away from the engine and are located on the “cat back” part of the exhaust,not the ones located on the downpipes,correct?

Also,do you guys know of any websites or tutorials that better explains how to use VCDS as a diagnostic tool. The info at Ross Tech and their Wiki is vague at best,imho. I really need to learn how to use VCDS a bit better. I know only how to do very basic stuff.

Thanks agan for your replies.