Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the logical successor to CHARM, I recommend you try it!

Link: lemon-manuals.la

Fuel Trim Cell

Scan Tool displays cell#. Fuel trim cell is dependent upon engine speed and MAF sensor readings. A plot of RPM vs. MAF is divided into 10 cells. Fuel trim cell indicates which cell is currently active.