I have a 2008 nissan maxima SE and I'm getting the code p0840 which is the transmission fluid pressure sensor. I was told that I have to replace the whole transmission to fix it and I wanted to know if that's true? Also I'm not seeing the P for park nor the N for neutral when I put it in gear. So is it the TCM that's the issue, the pressure sensor or both? I just wanted to know before I get rid of it for a low low price and take a lost. All this happened after I had all 4 O2 sensors replaced 6 months ago and I haven't been able to drive it since. The car was fine until I did that.
The Jatco CVTs that Nissan uses are known to be of poor quality and it would not be surprising for it to fail. (15 years is a really good run for one of those.) However if this happened right after replacing O2 sensors I'd look to see if wiring going into the transmission has been disturbed.
please post the entire diagnostic fault. It's never just "transmission fluid pressure sensor". It usually describes the specific problem.
