P0841 Code on 2008 Auto Mazda5

[personality]

Everything I've read so far points to the Transmission Fluid Pressure Switch. Can anyone tell me where that actually is and how to replace it?

The CEL light did not come on, but I checked the fault codes after noticing I got 18mpg's out of a half tank of gas, which was unusually low. I have not noticed any unusual shifting.
Car has 130k miles, 7k of which are mine. The fluid was pretty nasty when I got the car, and I've done 3 drain and fills since.

I just checked the fluid level, and if anything it looks a little high. Color is OK

 

[Silentnoise713]

I just started getting P0841... I just hope it really is a faulty pressure control solenoid and not the TCM (also getting U2064 - Network).
Not hard to replace, but does take time b/c you need to drop the transmission pan to access it and will need to clean the OE gasket compound before you can put on a replacement gasket. Once you drop the pan, it's in sight. Think of this as your time to do a complete transmission fluid/filter change.

https://www.mazdas247.com/forum/sho...-B-questions&p=6330972&viewfull=1#post6330972

https://www.mazdas247.com/forum/sho...-Automatic-Transmission-Fluid-Pressure-Switch

 

[personality]

You need to drop the transmission to replace the pressure control solenoid?

 

[Silentnoise713]

Not the whole transmission, just the "pan". See link above, look at diagram.

 

[Swenny]

Just to re-affirm, P0841 is for the Pressure Control Switch, not the Solenoid.

You do not need to drop the pan to replace the switch, but ATX fluid will come out when replacing it. I would consider draining out the fluid from the bottom of the pan first, then inspect/replace the switch.

Curious if everyone who has gotten this code has changed their ATX fluid from stock to something else. If the aftermarket stuff is "heavier", it may be causing the PSI to be out of spec, hence throwing the error.

 

[Silentnoise713]

Swenny is right. The 'switch' is external, tucked away next to the oil cooler. Since it is located above the transmission pan line, you should not need to draining the tranny fluid. I thought I read that the P0841 was due to solenoid, which is inside the case. That said, I had P0841, replace solenoid (+ new fuild b/c drop pan) and now no more P0841. Its possible that the P0841 is a symptom caused by something else. It's easy access and worth inspecting.


See bottom pic in 1st post, far right

https://www.mazdas247.com/forum/sho...a5-Oil-Cooler-Replacement-amp-YOUTUBE-WARNING

Part# FNE2212J1A
Generic# Standard Motor Products PS-543

Kinda pricey for such a simple device. I see many 'suspiciously' similar pressure control 'switches' for Honda for less than half the cost...

 

[Silentnoise713]

P0841 and U2064 are back... Funny thing is these two do not trigger a CEL by itself. I got P0455 b/c the NJ gas attendant didn't close the cap tight. Check to reset it and only then did I see P0841 and U2064 lurking...

Changed the valve. VERY easy to do. Remove two 12mm bolts and tie the trans oil cooler aside. Unclip the valve and use 22mm deep sock to remove and install new one. No need to drain trans oil. It does not leak, at most weeps a drop or two of fluid.

I suspect that valve itself is not failing, per say, but rather there's small metal particle build up inside the valve affecting it's ability to ready correctly. Old fluid gets contaminated by microscopic metals from wear and tear that causes all sorts of problems a in a transmission (REPLACE YOUR FLUID). That or the TCM or wiring is bad which I don't thing bc the trans shifts/works otherwise.