If you are having trouble with your vehicle and the code P0871 appears, there is no need to panic. This code indicates that there is a problem in your transmission fluid pressure sensor circuit, which may be causing it to malfunction. To fix this issue, it's important to first locate the Transmission Fluid Pressure Sensor (TFPS). It is typically located on the side of the transmission near where the shift linkage connects. Once you have found this component, disconnect its electrical connector and inspect it for any signs of corrosion or damage. If present, clean or replace as necessary before reconnecting and testing again. Additionally, check all wiring harnesses connected to the TFPS for breaks or corrosion as well as look for loose connections at both ends of all related wiring connectors. Finally verify that power and ground circuits are providing correct voltage levels when tested with a multimeter set to DC Volts mode. Following these steps should help resolve code P0871 and get your vehicle running optimally again!