RS4 B7 HIGH NIGATIVE LONG TERM FUEL TRIM

[Dinosroume]

Hey i'm getting high negative long term fuel trims for a while.
The car runs fine but not performs as it should and sometimes i get this fault code fuel trim too rich.(Sometimes on both banks)

My Lambdas has been replaced 15.000km ago and carbon cleaned almost 8.000 kms too.

Anyone who can guide me where to start and what to check ?

[Kenny147]

Just to confirm it’s running rich, have you pulled the spark plugs to see what condition they’re in?

Also, were the O2 sensors genuine VAG or aftermarket? I’ve heard of people using Bosch sensors but getting the wrong parts because it’s not always easy to work out what the correct Bosch part numbers, are.

[Dinosroume]

Just to confirm it’s running rich, have you pulled the spark plugs to see what condition they’re in?

Also, were the O2 sensors genuine VAG or aftermarket? I’ve heard of people using Bosch sensors but getting the wrong parts because it’s not always easy to work out what the correct Bosch part numbers, are.

I'm running stage 2 decat but i can smell a lot of fuel. My O2 sensors are bosch i'll send you the box part number but i'm 100% they are the correct because i bought them with the oem part number code and the car was running fine.

Also my fuel consuption has been increased lately.

I'll try to clean my 02 sensors because i was running decat without stage 2 map for a few weeks before stage 2 installed and i wonder if they o2 sensors are dirty and can't read correct.

Dinos

[Kenny147]

I recently fitted catless DP’s and the mechanic who did the work completely killed the connector on the rear, bank 2 O2 sensor. Ran very rich and the smell of petrol was overwhelming.

Fitted a new VAG O2 sensor and there was an immediate change back to normal fuel trim and MPG.

I would be surprised if it’s not the rear O2 sensors, personally.

[Dinosroume]

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[Dinosroume]

I recently fitted catless DP’s and the mechanic who did the work completely killed the connector on the rear, bank 2 O2 sensor. Ran very rich and the smell of petrol was overwhelming.

Fitted a new VAG O2 sensor and there was an immediate change back to normal fuel trim and MPG.

I would be surprised if it’s not the rear O2 sensors, personally.

I did the installation by myself and my cars never see mechanics or dealerships so i'm sure i didn't kill the connector.
Did you change the Bank 2 s2 sensor?
You replaced the rear O2 sensor that checks the cats efficiency.

The rear O2 sensors have 4 pin connector and the front has 6 pin connector. Which one did you replace?

[Kenny147]

The rear, right side O2 sensor. There was an immediate change for the better of Mpg.