Where to check transmission fluid on a 2003 nisann sentra ser spec-v?

The engine & transmission are mounted laterally. The engine is on the passenger side and transmission on the driver's side (assuming a U.S. layout with driver on the left).

You have to remove the speedometer pinion assembly, which is located on the driver's side of the transmission. It is a small gear assembly that inserts into a hole in the transmission. The top of the pinion assembly covers the hole, so once you remove it you can check the transmission oil level and add more oil if necessary.

You have to reach down into the engine bay about 2 feet to grab it. You will be almost up against the firewall between engine bay and passenger compartment.

There is a wiring harness plugged into the top of the assembly. Press the tab with your thumb, and pull it out sideways. Next to it is a 10mm nut that you will need to loosen. This nut holds the top plate of the assembly down onto the transmission casing. Once you get the nut loosened and removed, carefully pull the assembly straight up. You might have to gently rotate it back and forth to get it to pull out.

Be careful of the O-ring seal when pulling it out and putting it back in. Also, keep it clean to avoid introducing dirt/debris into the transmission when you re-insert it.

I used a clean strip of metal as a dipstick to check the fluid level. The Chilton's book I have says correct level is 1 1/2" below the opening for the 2.0 liter engine, but it doesn't say anything about the 2.5 liter engine which is what the Sentra SE-R has. So, I just used this level.

When re-inserting the assembly, just slide it back down in, but don't force it. Rotate back & forth while pushing if necessary until the assembly's top cover is flush with the transmission casing. Tighten the nut back down and re-connect the wiring harness.