2004 Toyota Sienna O2 Sensor Fault: P2238 and P2241 Codes After Replacement
I've been experiencing check engine light issues on my 2004 Toyota Sienna, with fault codes P2238 (Current control circuit low for bank 1 sensor 1) and P2240 (Pumping current circuit low for air/fuel ratio sensor bank 2 sensor 1). I followed a forum guide to replace the oxygen sensors as recommended, and after the replacement, the engine runs smoothly with no noticeable performance issues. The electrical connections appear intact, and I've driven extensively on the freeway to allow the system to reset naturally. However, the codes persist. I'm wondering whether I need to manually reset the check engine light by disconnecting the battery, or if there's another underlying cause. Since the vehicle has been driven over long distances, I suspect it might not be a PCM issue—what should I do next? Any advice on troubleshooting steps would be greatly appreciated.
Could you please share the manufacturer and part numbers of the oxygen sensors you replaced? Additionally, it would help to know your fuel trim values at idle and at 3000 RPM. If the codes have not reset after driving, disconnecting the battery should clear them and refresh the KAM (Kamal Adjustment Module) settings. This step is often effective for resetting the system in older Toyota models like the Sienna.