What does it mean?
In a vehicle with an automatic transmission, transmission fluid is pressurized with a pump to hydraulically control the transmission and switch gears. If the fluid pressure isn’t within the specified range, the transmission can cease proper operation, or sustain damage. The P0874 Transmission fluid pressure sensor will illuminate the check engine light when the transmission fluid pressure falls outside the range predetermined by the manufacturer.
In some cases, the P0874 error will cause the vehicle to enter “limp home” mode. When this code is present, the vehicle should not be driven as severe transmission damage could result. Note: “switch C -intermittent circuit malfunction” is a code that will identify which sensor is showing out of range. Your model specific service manual or parts catalog will identify which sensor is “switch C.