I am trying to narrow down reason for bad mpg and high long term fuel trim (+9 or 10 avg) at low speeds and figure it is either a bad bank 1 cat or an exhaust leak somewhere before the Bank 1, Sensor 2 Heated O2 sensor.

So I crawled under the car tonight and took a picture of the header. Does that gap between the header and the block look normal? I would think it would have more soot/exhaust burn around the area if it was the cause of the leak, but yet it doesn't look normal to me either. Any help would be appreciated. C. (2007 ES-350)


bottom of bank 1 header

 

There doesn't appear to be a leak and the header to head fit looks normal. You are correct if there was a leak you would have a lot of black in the area.

 

Jagtoes,
Thank you!