View Full Version : Are these the right CELs for a HFC?

11-16-2009, 11:11 PM
Car: 2000 Audi A4 ATW, with Labree HFC


16806 - Main Catalyst: Bank 1: Efficiency Below Threshold
P0422 - 35-00 - -
16524 - Oxygen (Lambda) Sensor B1 S2: No Activity
P0140 - 35-00 - -

So i am wondering if these are the right codes to be getting with a Labree HFC, the "efficiency below threshold" doesn't shock me so much, its the "no activity one" that gets me. Is that right? I just installed a new rear o2 sensor and am getting the same codes.

I was thinking of doing the non-fouler mod, but the rear o2 sensor is already a good 1.5" out of the exhaust stream as the threaded input for the rear o2 sensor is connected to an extended tube to pull it out of the exhaust flow (see pic below).

So what exactly is the 'no activity code' saying? Is it a wiring issue, or is it just something that goes along with the HFC and should try using a non-fouler? Seems like one is saying its "reading the wrong value" and one says its "not reading at all" so just curious how it can have both.

Any input would be great, thanks!

Pic to show the extended tube for the rear o2 sensor bung on the Labree HFC (you can see it in the top right of the picture):

11-16-2009, 11:22 PM
1st one seem right, well I get that with my Testpipe

11-17-2009, 12:00 AM
I got the code for no activity when my rear O2 was bad. I got that code and a heater open circuit code. I replaced the rear O2 and both went away. I guess I'd try a spacer first in your case. It can't hurt.

11-17-2009, 03:22 AM
I recieve either one or both of those codes when I get a CEL for my Labree HFC. If your 02 sensor was faulty, it should not pass readiness. I replaced my rear 02 sensor mainly due to that code (and for a different reason). And I still get that CEL on occassions when I get a CEL for my HFC, so they are indeed associated.

11-17-2009, 08:13 AM
use this code, it will fix all your problems. ;) starts @ 18194 in hex.


11-17-2009, 08:18 AM
use this code, it will fix all your problems. ;) starts @ 18194 in hex.


I love the techiness of this answer - Any chance you will tell me where the blocks are for setting readiness? ;)

11-17-2009, 08:23 AM
that code disables readiness checks. see?


i also did this edit:





and the result:


theres fault codes because i never cleared them after reinstalling ecu. but whats important is what you dont see a fault for. ;)


11-17-2009, 08:42 AM
Awesome....I take it that picture is of your SAI - or lack thereof?

11-17-2009, 08:45 AM
no need to quote everything. that picture is of missing rear o2.

11-17-2009, 10:14 AM
kompresd... what stuff do i need to pull that off!

I had the stock cat, and started getting the 'efficency below threshold' code, then after i installed the HFC i started getting both the 'efficiency' and 'no activity' code, but i thought i might have damaged the rear o2 sensor when pulling the stock cat out. But now that i've thrown a new one in there and am getting the same codes i was confused because i didnt expect the 'no activity' code

11-17-2009, 11:28 AM
galetto clone + cracked winols will do it.

11-17-2009, 12:20 PM
/\ /\ kompresd, much thanks!

does anyone know what the "no activity" code is saying? is it saying that the ecu cant communicate with the sensor, or is it saying that the sensor isnt reading anything.

also wondering if anyone knows what the pinouts are supposed to be on the connector or a way to test the sensor itself.

11-17-2009, 09:05 PM
is there anything i can test to get a better idea of whats triggering the no activity code? like an ohm test on the o2 sensor or voltage check on the ecu side connector?

11-17-2009, 09:11 PM
hex edit = no need for testing.

11-17-2009, 09:15 PM
hex edit = no need for testing.

haha i know i know i am being gun shy about pulling the trigger on buying the setup, but i really know thats the route i am going to end up taking... especially since i like working with stuff like that

if the chip was soldered in can it still be read and reflashed?

11-17-2009, 09:30 PM
as long as its a normal eprom with no encryption board i would assume its ok.

11-17-2009, 09:46 PM
well seems like we are going to find out then! lol

i'm going to order the stuff tomorrow and see what happens!

x Wild Bill x
11-23-2009, 09:20 AM
Just wondering if you got the stuff in and took care of the code?
Maybe an update was lost when the site crashed...