Monitor Description

WARNING: This page is about a different car, the 2018 Toyota Sequoia, 2017 Toyota Sequoia, and 2016 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.

Fuel System Air-fuel Ratio Cylinder Imbalance Monitor

The ECM uses the air fuel ratio sensor and crankshaft position sensor to monitor the difference in air-fuel ratios between the cylinders caused by differences in injection volumes between the cylinders, leakage in the intake or exhaust system, etc.

When the air-fuel ratios of the cylinders are lean or rich with respect to each other, the ECM determines that a problem is present and stores a DTC.

Air Fuel Ratio Sensor Monitoring Method: P219A and/or P219B are stored primarily when a rich side imbalance is detected.

When the system detects a difference in air-fuel ratios between the cylinders due to fluctuation in the air fuel ratio sensor output over 1 engine cycle (2 crankshaft revolutions), the system determines that there is a problem.

Crankshaft Position Sensor Monitoring Method: P219C, P219D, P219E, P219F, P21A0, P21A1, P21A2 and/or P21A3 are stored primarily when a lean side imbalance is detected.

The system monitors the engine speed variation and when the variation becomes large, the system determines that there is a difference in air-fuel ratios between the cylinders, which it determines to be a problem.