Rick's Free Auto Repair Advice

Kia P2096 Post Catalyst Fuel Trim System too Lean (Bank 1)

Kia P2096 Post Catalyst Fuel Trim System too Lean (Bank 1)

Diagnose and fix Kia P2096 Post Catalyst Fuel Trim System too Lean (Bank 1)

Kia constantly monitors the upstream and downstream oxygen sensors and constantly changes fuel trims to compensate for rich/lean readings. To properly diagnose a Kia P2096, read the live data on a scan tool for the upstream and downstream oxygen sensors.

screw in oxygen sensor

Screw in oxygen sensor

The upstream sensors should rapidly switch from low to high voltage while the downstream sensor should stay at around 0.6-0.7-volts.

If your readings show rapid switching or switching at higher lower rates at the downstream oxygen sensor, that can be an indication of:

1) Vacuum leak on engine. Check for cracks in the air duct from the air filter box to the throttle body. Check for cracked or unhooked vacuum lines. Check for vacuum leaks in and around the intake manifold.

2) Exhaust leak ahead of the catalytic converter. To test, connect a shop vacuum to the tailpipe in the “blow” mode. Using a spray bottle filled with water and dishwashing detergent, spray each joint on the exhaust system, looking of bubbles that would indicate a leak. Repair as needed

3) Disconnect the connector to the downstream oxygen sensor and check terminal condition. Clean any corrosion and twist the male terminal approximately 10° to obtain a better connection.

If the problem persists, replace the downstream oxygen sensor.

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Posted on by Rick Muscoplat

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