Where do I find speed sensors on a 2003 Nissan Murano?

code p 0720 refers to output shaft speed (OSS) sensor ---circuit malfunction===causes --wiring--OSS-- ECM --TCM( transmission control module
If you didn't have the code before , check for wire connections to the transmission after the exhaust work
code p 0420 refers to cat converter system bank 1--efficiency below threshold ===causes --cat converter---wiring HO2s (heated oxygen sensor in the exhaust manifold before the cat converter) code p 1574 refers to the vehicle speed sensor , VSS
again check wiring and connections or replace the VSS

According to the database the code means OUTPUT SPEED SENSOR CIRCUT MALFUNCTION.

You need to have the transmission check for codes and operation concerns.

This link may be helpful.
Bob

https://www.google.com/url?sa=t&source=web&rct=j&ei=jVO4VK_hEMvbsAT83YDgCA&url=http://www.autopartswarehouse.com/shop_years/nissan-sentra-speed-sensor-2001.html&ved=0CDcQFjAA&usg=AFQjCNHmI3zYnmpPLAMrWGUYw4Hq3dw2tQ&sig2=NZHLkkBawd1OUJEZgAwLQQ

This is way over the head of the home repairman, you will need the dealer to look into these codes.

p1574 = "throttle position sensor disagreement btwn sensors"
p0720 = "Vehicle Speed Sensor"

hope this helps you out.

p0720-- auto. trans. vehicle speed sensor (revolution sensor)

p1574--automatic speed control device/vehicle speed sensor

p0420--two way catalyst system bank 1

I have a 2002 Nissan Altima. Can anyone tell me what these codes are? And how to fix them? P0420

P1529 indicates that your TCM asked the ECM to turn on the check engine lamp.

The range switch and the output speed sensors are the items that are abnormally affecting the operation of the transmission. The diagnostic logic in your computer can distinguish these issues from one another, so you'll definitely want to do both. You have no diagnostic code for the input speed sensor (P0715) listed, so I have made no recommendation to replace it. In my opinion, it's not a labor-intensive repair, so I wouldn't recommend replacing it unless you have reason to believe it's bad.

DTC - P0720 (OUTPUT SHAFT SPEED SENSOR SYSTEM)
Code No. P0720 Output shaft speed sensor system
If the output from the output shaft speed sensor is continuously 50% lower than the vehicle speed for 1 second or more while driving in 3rd or 4th gear at a speed of 30 km/h or more, it is judged to be an open circuit or short-circuit in the output shaft speed sensor and diagnostic trouble code No. P0720 is output. If diagnostic trouble code No. P0720 is output four times, the transmission is locked into 3rd gear or 2rid gear as a fail-safe measure.
Probable cause
Malfunction of the output shaft speed sensor
Malfunction of the transfer drive gear or driven gear
Malfunction of connector
Malfunction of the TCM

DTC - P0715 (INPUT SHAFT SPEED SENSOR SYSTEM)
Code No. P0715 input shaft speed sensor system
If no output pulse is detected from the input shaft speed sensor for 1 second or more while driving in 3rd or 4th gear at a speed of 30 km/h (19 mph) or more, it is judged to be an open circuit or short-circuit in the input shaft speed sensor and diagnostic trouble code No. P0715 is output. If diagnostic trouble code P0715 is output four times, the transaxle is locked into 3rd gear or 2nd gear as a fail-safe measure.
Probable cause
Malfunction of the input shaft speed sensor
Malfunction of the underdrive clutch retainer
Malfunction of connector
Malfunction of the TCM

Is needed replace.

there is a emission system recall for these codes for your year and model contact the Nissan dealer, it is a no charge repair.
here is the summary of that recall

MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P0300-P0306, P1273 OR P1283. *TT *SC
Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.
Service Bulletin Number : 04028A Date of Bulletin : MAR 24, 2004
NHTSA Item Number : 10005976
Component : ELECTRICAL SYSTEM
Summary :
MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P1031, P1051, P1148, P1168 (A/F SENSOR HEATER / CLOSED LOOP) ON 5 SPEED AUTOMATIC TRANSMISSIONS ONLY. (THIS VERSION SUPERSEDES NTB04-028.) *TT