Reset Fuel Trims?

[Dave_Ally]

Hi all, so I have just replaced the front oxygen sensor with a genuine Bosch job for my car. However, long term fuel trim is still at 20%. I have tried forcing a fault code and clearing it but this didn't clear the fuel trim. Car seems a lot more driveable now but I'm worried that now it's adapted to 20-23% long term it needs to relearn. Will pulling the battery reset everything learnt or will it take some specialist scan equipment? This is OBDII by the way.

 

[r-reg-sr]

coolant temp sensor is another one to check
injectors? fuel pressure?

 

[Dave_Ally]

Coolant starts off low and goes up to about 88-91C when warmed up and stays there. I just think the trims need reset after the swap or maybe I need to do a long enough drive to allow it to learn from the new sensor?

 

[davey1991]

Takes about 200miles.

 

[Dave_Ally]

OK cheers davey1991, I'll just take it for a drive into the Lakes at the weekend. (Y)

 

[Dave_Ally]

Just to update, they never went back to 0 after 500 miles, in the end I gave up hoping the ECU would do it's adaptation and pulled the battery negative lead for 3 hours which reset the trims. Had the gases tested before MOT and they checked out fine as well as live data from O2 sensor and MAF sensor which are working well. (Y)

The fuel trims would not reset electronically, the battery had to be disconnected for them to return to 0. Time will tell if they stay there.

 

[essexpunx]

Did this with mine, disconnected the battery, been fine for 3000 miles (Y)

 

[davey1991]

Ahh well mine reset after driving 200 miles maybe i'm just lucky...

 

[Dave_Ally]

Mine were swaying between 14-17% occasionally dipping each way so it didn't seem like the ECU was making the big adaptation to bring it down.