Mazda CX-5 6-speed Auto P0841 Code and Harsh Shifting

Question

My 2016 Mazda CX-5 is starting to shift very hard between 2nd and 3rd gear, and sometimes it feels like it's slipping under light acceleration. The check engine light came on yesterday with code P0841. I am worried the whole transmission is going out, but it only happens once the car is fully warmed up.

wrenchqueen · Accepted Answer

The issue was settled by replacing the Oil Pressure Switch #1 (small tan sensor) located on the valve body inside the transmission. I removed the pan and the oil strainer, then swapped the switch using a 27mm deep socket; the switch part number was BJS7-21-2C1. While inside, I also replaced the ATF with 5 quarts of Mazda FZ fluid and the filter. The car shifts perfectly now and the total cost for parts was about $140.

Dave Kowalski · Answer

Check the wiring harness connector at the transmission case for any ATF wicking into the pins. If the connector is dry, you likely have a failing oil pressure switch on the valve body; these fail internally quite often on the SkyActiv units.

torque_terry · Answer

Before swapping parts, drop the pan and check for excessive metal debris. If the pan is clean, it's just the pressure switch. If there is heavy silver glitter, the internal bearings are wearing out and clogging the small screens inside the solenoid block.

Marcus Bell · Answer

You need to monitor the live data for Oil Pressure Switch 1. If it stays OFF when it should be ON during gear transitions, the TCM triggers P0841. Sometimes a simple TSB software update for the TCM can widen the logic parameters, but usually, it is a hardware failure.

Mazda CX-5 6-speed Auto P0841 Code and Harsh Shifting

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