Fault codes, P2004 & P1923

[Stile]

Hey,

I tried to search, but no luck. So I make a new topic. Sorry for that.

Patient is RS6 C6 2008, 84k miles. The previous owner has installed KWE downpipes with race cats and ecu tune. A few days ago I installed KWE 3" exhaust.

Yesterday I got two times P0056 H02S Heater Control Circuit (Bank 2 Sensor 2). I clear the codes and the engine warning light show no more.

Today got message "Do not exceed 4000 rpm" and;

P2004 Intake Manifold Runner Control Bank 1: Stuck Open

P1923 Check DTC memory of: Engine Control Module (ECM) 2

With those no engine warning light. It feels weird that there are two very different faults at the same time. Idle and startup is normal.

Regards,
Stile

[ATinOf]

Ive not had the 2 codes you state but Im guessing...

You sometimes get the second code P1923 if you have cleared faults from ECU1 (VCDS controller address 01) and left related faults sitting in ECU2 uncleared
Try clearing DTC in ECU2 (VCDS controller address 11)

P2004 is your intake manifold runner flaps, opened and closed by the vacuum diaphragm mounted under your inlet manifold centrally on the inner side of your head (in your case bank 1) and controlled by an actuator between it and the vacuum reservoir (again under your inlet manifold). Its likely one or more of the flaps is binding and stuck, as the code states

P0056 is post cat bank 2 oxygen sensor heater circuit fault - if its gone away its an intermittent electrical issue or the sensors heater is on its way out. You can check the status and ageing of the oxygen sensors through VCDS, check the ross-tech wiki

[Stile]

Hey,

thanks ATinOf for a good answer! I ordered VCDS.

Meanwhile I got;

P0153 O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)
P0057 HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
P0037 HO2S Heater Control Circuit Low (Bank 1 Sensor 2)

I believe that everything is related to 3" exhaust system..

[5oren]

Hi Stile,

I just got the same P2004 code showing up (RS6 2010), at the beginning it was on and off but after a few days it is on all the time.

What was problem in your case and how did you fix it?

Cheers Soren

[c3nturi0n]

here is bit of a feedback that may not assist in your quest but it got me into thinking on few occasions, e.g. how useful codes / VCDS is in a non-MIL related situations?

At times i do get boost pressure related errors (and no MIL). Cars works fine w/o any noticeable drops in power or delivery. However i only noticed that i get those when i use 95 octane fuel. So i guess for me, and not to get fuel boos issues, is to only use 97 or 99 octane. As suggested, not much of help to you, but error codes (to me at least) are only useful when you have noticeable performance or drive related problems.

and by all means, i'd suggest to invest in VCDS (plenty of examples / copies available on net / fleebay).

All the best!