P0139

DTC P0139: Secondary HO2S (Sensor 2) Slow Response

1. Reset the ECM with the HDS.
2. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
3. Check the HO2S S2 at 3,000 rpm in the DATA LIST with the HDS.

Does the voltage stay within 0.3 - 0.6 V for 2 minutes?

YES - Replace the secondary HO2S (Sensor 2), and the third HO2S (Sensor 3)*.
* 1: 2002-2005 M/T models

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM.