Chrysler
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Fuel System Rich Conditions
Cause:
    ECT sensor input more than 170°F, engine running in closed loop, BTS input over 20°F, altitude under 8000 ft., then the test started and the PCM detected a fuel injector command that reduced injector pulse-width by 25% LONGFT along with a 7% Short term compensation command (due to a rich air/fuel mixture condition).

Ford
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Fuel System Too Rich Conditions
Cause:
    Engine running at Cruise speed for 3-4 minutes, then the PCM detected that the Adaptive Fuel Control System was at its lean correction limit (due to a rich A/F ratio)

Generic
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    System Too Rich

GM
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Fuel Trim System Rich Conditions
Cause:
    Engine running at steady speed in closed loop, IAT sensor input from 14-158°F, BARO input over 75 kPa, fuel tank level over 25% and the PCM detected the LONGFT value was over -30% for 5 seconds, or the SHRTFT value was over -20% for 45 seconds

Nissan
Type:
    Powertrain - Fuel and Air Metering - ISO/SAE Controlled
Description:
    Fuel trim - Bank 1 - mixture too rich
Cause:
    Wiring, intake/exhaust system, HO2S front, fuel system, injector, MAF sensor, ECM