hey so previously in the threads we been talking about my bad gas millage so imthedevil said the its a bad 02 sensor now on vagcom the car says its running to rich which im guessing o2 sensor i did the clean the mas air flow sensor soo which 02 sensor do i need to order he said the one closest to the engine like a pre car one or somthing any idea's ?

http://www.ecstuning.com/Audi-B5_A4-...ne/Electrical/

 

anyone?

 

you need the front position o2 sensor(s)...even though you cleaned your maf, it MIGHT need replacing.

 

thanks man

 

Yep, the primary (pre-cat) sensor is what the computer uses to measure unburned oxygen and, frombthat, to determine what the fuel mixture should be. The secondary (after-cat) sensor is used on a comparison basis to the first so the computer can get an idea how well the cat is functioning. When the primary starts to crap out and the computer decides its signals are unreliable for determining the mixture, it ignores the sensor and defaults to preprogrammed rich-fuel maps in order to safeguard the engine, and it trips a CEL to let you know that it suspects the O2 sensor to be faulty.

 

alright you are the man imthedevil idk how many times you have helped me out so im looking at buying this one http://www.ecstuning.com/Audi-B5_A4-...trical/ES2611/

 

Looks good but for what it's worth we used a generic O2 sensor from Advance Auto on a 30v and it works perfectly. Costs $70. You have to splice it onto your harness but it's easy. Also, since it's a V6, you have two primary O2s, one for each cylinder bank. I'm assuming you used Vag to get a code - did you? I ask because it'll indicate bank 1 (passenger side) or bank 2 (driver side). If you're not sure which side is suspect, or don't have a code, you may want to do both of them, especially if they've been in there for a longer period of time. Either could be bad but both are probably wearing down if they've got a good number of miles on them.

 

Generic? I hope it was Denso or Bosch. I wouldn't touch other O2 sensor brands.

 

oh dang im gonna haft to look at the codes on the car its still at the dealer im getting it in the morning i think im gonna order one than figure out which one is bad and start there there might be 2 bad but idk it just brought up 4 codes for saying car is too rich its been awhile since ive looked at the car on vagcom prob 2 months

 

ddress 01: Engine Labels: 078-907-551-AHA.lbl
Mileage: 330540km/205388miles
Part No: 4D0 907 551 AH
Component: 2.8L V6/5V MOTR AT D02
Coding: 06251
Shop #: WSC 07343

8 Faults Found:
16825 - EVAP Emission Control Sys: Incorrect Flow
P0441 - 35-10 - - - Intermittent
17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - - - Intermittent
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-10 - - - Intermittent
17537 - Fuel Trim; Bank 2 (Mult): System too Rich
P1129 - 35-10 - - - Intermittent
17535 - Fuel Trim; Bank 1 (Mult): System too Rich
P1127 - 35-10 - - - Intermittent
17800 - Camshaft Position Sensor Bank 2 (G163): Open Short to Plus
P1392 - 35-10 - - - Intermittent
17547 - Fuel Trim: Bank 2 (Add): System too Rich
P1139 - 35-10 - - - Intermittent
17545 - Fuel Trim: Bank 1 (Add): System too Rich
P1137 - 35-10 - - - Intermittent
Readiness: 0000 0000