I reset the ECU and I gained gas?!

[KnightFiyah]

If you read my first thread a couple of days ago you'll know I had the very common P0420 code with my 2000 Toyota 4Runner SR5 (Cali Emissions). I changed the front A/F sensor and that was the end of it.

This is where things get interesting...

I disconnected the negative/black terminal of the battery today for ~10 mins to reset the ECU and get rid of the CEL. When I reconnected the battery and started the car, the CEL was gone but the car said I had 1/4 MORE gas than before I reset the ECU.

I only reset the ECU because I read somewhere that it's good to do so after you make any type of fuel/timing adjustments to the car (and the CEL was starting to annoy me...).

What explains this change in the car's reading of how much gas is in the car?
I'm not sure if the car is still "adapting" due to the reset of the ECU and the gas gauge is currently inaccurate or if the A/F sensor I replaced is doing work and the old one was really going bad.

Thanks in advance fellas.

 

[Rock_Rat]

One too many shots of Macallan 25 usually does it for me.( (We can all dream)

Honestly, no clue. The A/F sensor and tank qty are unrelated. You should know how many miles you average per fill up so I would watch the gauge and the miles and see if they correlate. If you're still an extra 1/4 tank and you've reached your known average mileage you need to fill it up and watch it again. It may "correct" itself. If not you'll have to get the wiring manuals out and try and follow the path of the qty sending unit.

I'm not up to speed on the fuel low level light but if it's a float type device there's a good chance the light may come on earlier than normal. Keep us posted. I'm curious as to what you find out.

And hey, stay away from the Macallan while doing mix on your 4Runner!! :cheers:

 

[kolelt]

Most likley, not!

 

[KnightFiyah]

One too many shots of Macallan 25 usually does it for me.

Honestly, no clue. The A/F sensor and tank qty are unrelated. You should know how many miles you average per fill up so I would watch the gauge and the miles and see if they correlate. If you're still an extra 1/4 tank and you've reached your known average mileage you need to fill it up and watch it again. It may "correct" itself. If not you'll have to get the wiring manuals out and try and follow the path of the qty sending unit.

I'm not up to speed on the fuel low level light but if it's a float type device there's a good chance the light may come on earlier than normal. Keep us posted. I'm curious as to what you find out.

And hey, stay away from the Macallan while doing mtx on your 4Runner!! :cheers:

Yeah it ended up just slowly correcting itself over the next 10 or so miles.
Thanks for the feedback regardless!

 

[jgue467]

Nice dreams!