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 spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Fuel Trim System Monitor Diagnostic Tests

The fuel trim monitor diagnostic tests monitor the fuel trim values. When the diagnostic tests indicate that the fuel trim system has reached the limits of fuel control at certain engine operating conditions, a fuel trim DTC will set.