What would be the most obvious sign that a primary O2 sensor is bad beyond a CEL?

Fast Euro · 05-16-2006, 06:20 AM

Anything else to look for?

lemieux@curbside · 05-16-2006, 07:04 AM

on one pipe if one reads low and inconsistent while the other reads high and steaday ..you have a bad 02

se the pic here the yellow is bad .. se how it reads compared to the one down stream ( bank 2 = driver side pre TWC = before cat up top)

Fast Euro · 05-16-2006, 07:21 AM

...some member wrote how his car drove so much better after replacing his O2 sensors.

lemieux@curbside · 05-16-2006, 07:24 AM

it wouldn't just die .. so u'll be somewhat use to it .
just log and see .. but if you have the codes i'd just change the O2-s (i changed my primary ones together).

Fast Euro · 05-16-2006, 07:48 AM

..and I don't have any leaks in my system.

lemieux@curbside · 05-16-2006, 08:27 AM

log blocks 003 and 031 as soon as you can .. 3-rd gear WOT from 3000 rpm to 6500 rpm , and post the results.
what does block 032 look like (just #-s no logs needed)
i've seen a marginal working maf giving out o2 sensor codes .

Fast Euro · 05-16-2006, 09:11 AM

when the CEL comes one. Not sure if thats related directly to the issue or not.

Ah10@WMS · 05-16-2006, 09:45 AM

Swank4 · 05-16-2006, 10:05 AM

others have had rough idles and/or misfires. The O2s give info back to the ECU for air/fuel mixture so imagine what an improper air/fuel mixture can do and those would be your possible symptoms. In my case, the O2 was dying (intermittent) and my guess is that the ECU thought the mixture was too lean and so it dumped more fuel in...hence the bad gas mileage.

Fast Euro · 05-16-2006, 10:29 AM

05-16-2006, 06:20 AM	#1
Fast Euro AudiWorld Senior Member Garage is empty, add now Join Date: Feb 2006 Posts: 1,469	What would be the most obvious sign that a primary O2 sensor is bad beyond a CEL? Anything else to look for? __________________ ------------------------------------------- '01.5 S4 - 6 Spd - Stage 3- * K04 Turbos * GIAC-X/XR * ASP DP's+Tru-Dual Exhaust * Darintake & AWE S-Flo w/Dryflow element * 710N DV's * APR Bi-Pipe & Snub Mount * Hoen Fogs * RS4 shiftknob, grill, motor mounts * Low Temp T.S. * Vogtland Coilovers * ASP TSB * Topspin lip * AWE Pedals & Boost Guage (new style) * Hawk HPS pads * ECS slotted rotors * VAST Stg3 clutch Pearl White S4's

05-16-2006, 07:04 AM	#2
lemieux@curbside AudiWorld Super User Garage is empty, add now Join Date: Dec 2002 Posts: 17,781	log and compare .. one with the other 3 on one pipe if one reads low and inconsistent while the other reads high and steaday ..you have a bad 02 se the pic here the yellow is bad .. se how it reads compared to the one down stream ( bank 2 = driver side pre TWC = before cat up top) __________________ ************************************************ ************************************* "it's a B5 S4 ,it may break down, but its far enough ahead, by the time its fixed, you still haven't caught up." -best line i've heard AUDI B5 S4 detail info (pdf file) that everyone should read and have saved on his computer AUDI B5 RS4 study guide detail info (pdf file) FATS database VAG-COM LOCATOR ASP Hands down the "BESTEST" tuner out there.

05-16-2006, 07:21 AM	#3
Fast Euro AudiWorld Senior Member Garage is empty, add now Join Date: Feb 2006 Posts: 1,469	Besides logs, would it be noticable at all while driving? I STFA and read.. ...some member wrote how his car drove so much better after replacing his O2 sensors. __________________ ------------------------------------------- '01.5 S4 - 6 Spd - Stage 3- * K04 Turbos * GIAC-X/XR * ASP DP's+Tru-Dual Exhaust * Darintake & AWE S-Flo w/Dryflow element * 710N DV's * APR Bi-Pipe & Snub Mount * Hoen Fogs * RS4 shiftknob, grill, motor mounts * Low Temp T.S. * Vogtland Coilovers * ASP TSB * Topspin lip * AWE Pedals & Boost Guage (new style) * Hawk HPS pads * ECS slotted rotors * VAST Stg3 clutch Pearl White S4's

05-16-2006, 07:24 AM	#4
lemieux@curbside AudiWorld Super User Garage is empty, add now Join Date: Dec 2002 Posts: 17,781	u would notice a diff AFTER you change it i bet.. it wouldn't just die .. so u'll be somewhat use to it . just log and see .. but if you have the codes i'd just change the O2-s (i changed my primary ones together). __________________ ************************************************ ************************************* "it's a B5 S4 ,it may break down, but its far enough ahead, by the time its fixed, you still haven't caught up." -best line i've heard AUDI B5 S4 detail info (pdf file) that everyone should read and have saved on his computer AUDI B5 RS4 study guide detail info (pdf file) FATS database VAG-COM LOCATOR ASP Hands down the "BESTEST" tuner out there.

05-16-2006, 07:48 AM	#5
Fast Euro AudiWorld Senior Member Garage is empty, add now Join Date: Feb 2006 Posts: 1,469	Yeah, the code for the primary drivers O2 keeps coming up for me at least once a week.. ..and I don't have any leaks in my system. __________________ ------------------------------------------- '01.5 S4 - 6 Spd - Stage 3- * K04 Turbos * GIAC-X/XR * ASP DP's+Tru-Dual Exhaust * Darintake & AWE S-Flo w/Dryflow element * 710N DV's * APR Bi-Pipe & Snub Mount * Hoen Fogs * RS4 shiftknob, grill, motor mounts * Low Temp T.S. * Vogtland Coilovers * ASP TSB * Topspin lip * AWE Pedals & Boost Guage (new style) * Hawk HPS pads * ECS slotted rotors * VAST Stg3 clutch Pearl White S4's

05-16-2006, 08:27 AM	#6
lemieux@curbside AudiWorld Super User Garage is empty, add now Join Date: Dec 2002 Posts: 17,781	what maf do you have ? log blocks 003 and 031 as soon as you can .. 3-rd gear WOT from 3000 rpm to 6500 rpm , and post the results. what does block 032 look like (just #-s no logs needed) i've seen a marginal working maf giving out o2 sensor codes . __________________ ************************************************ ************************************* "it's a B5 S4 ,it may break down, but its far enough ahead, by the time its fixed, you still haven't caught up." -best line i've heard AUDI B5 S4 detail info (pdf file) that everyone should read and have saved on his computer AUDI B5 RS4 study guide detail info (pdf file) FATS database VAG-COM LOCATOR ASP Hands down the "BESTEST" tuner out there.

05-16-2006, 09:11 AM	#7
Fast Euro AudiWorld Senior Member Garage is empty, add now Join Date: Feb 2006 Posts: 1,469	Its the Hitachi. Funny that you say 3rd gear, because thats usually the gear I'm in.. when the CEL comes one. Not sure if thats related directly to the issue or not. __________________ ------------------------------------------- '01.5 S4 - 6 Spd - Stage 3- * K04 Turbos * GIAC-X/XR * ASP DP's+Tru-Dual Exhaust * Darintake & AWE S-Flo w/Dryflow element * 710N DV's * APR Bi-Pipe & Snub Mount * Hoen Fogs * RS4 shiftknob, grill, motor mounts * Low Temp T.S. * Vogtland Coilovers * ASP TSB * Topspin lip * AWE Pedals & Boost Guage (new style) * Hawk HPS pads * ECS slotted rotors * VAST Stg3 clutch Pearl White S4's

05-16-2006, 09:45 AM	#8
Ah10@WMS AudiWorld Super User Garage is empty, add now Join Date: Aug 2000 Posts: 7,611	Piggiesmalls: Another graph that captures this for visual learners... __________________ WMS: 818-997-6500 ASP:856-772-9500 \|\| ASP Custom Tuned Stage 3 \|\| 710P \|\| Piggie DP \|\| ASP 89mm Truedual \|\| ASP TSB \|\| APR Boost Gauge \|\| RS4 Grille \|\| \|\| AWE Intercooler \|\| C M Stage 4, 6 puck & LWFW \|\| ASP Motor Mount \|\| RS4 Tranny Mount\|\| StaSIS Motorsport Ohlins \|\| \|\| 18" Work W-ITS 901 \|\| 245/35/18 ContiSport3 \|\| Ecode \|\| Modded RS4 Bumper \|\| StaSIS Motorsport Alcon 6pot 355 \|\| WMS Stage III: 3.54 fats on Pump 3.25 fats on Race gas both runs were on pump file 3.06 on East Coast Pump Gas/Race File 2.93 on East Coast Pump Gas/Race File in 40f weather

05-16-2006, 10:05 AM	#9
Swank4 AudiWorld Super User Garage is empty, add now Join Date: Aug 2002 Location: San Francisco Posts: 6,764	Possibly. I had bad gas mileage and that was it... others have had rough idles and/or misfires. The O2s give info back to the ECU for air/fuel mixture so imagine what an improper air/fuel mixture can do and those would be your possible symptoms. In my case, the O2 was dying (intermittent) and my guess is that the ECU thought the mixture was too lean and so it dumped more fuel in...hence the bad gas mileage.

05-16-2006, 10:29 AM	#10
Fast Euro AudiWorld Senior Member Garage is empty, add now Join Date: Feb 2006 Posts: 1,469	Yeah, I'm getting an intermittent code as well. Well I have some Zoldmans on order so we'll see. __________________ ------------------------------------------- '01.5 S4 - 6 Spd - Stage 3- * K04 Turbos * GIAC-X/XR * ASP DP's+Tru-Dual Exhaust * Darintake & AWE S-Flo w/Dryflow element * 710N DV's * APR Bi-Pipe & Snub Mount * Hoen Fogs * RS4 shiftknob, grill, motor mounts * Low Temp T.S. * Vogtland Coilovers * ASP TSB * Topspin lip * AWE Pedals & Boost Guage (new style) * Hawk HPS pads * ECS slotted rotors * VAST Stg3 clutch Pearl White S4's

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