P0874: Transmission Fluid Pressure Sensor/Switch C Circuit Intermittent

Transmission fluid pressure switches C and D report whether a clutch circuit is pressurised. They are more widespread than A and B: GM's 6L80/6L90 and 6T40/6T70 six-speeds put switch C on the 2-6 brake and D on the 1-2-3-4 clutch, Allison uses them for its third shift valve and its reverse switch, Ram's RFE gearboxes for the clutch pressure switches in the solenoid block. Ford reports pressure faults under its solenoid codes. P0874 reports short dropouts or flutter of the C signal without a lasting low or high. It is documented only in GM bulletin 21-NA-033 for the Corvette C8 dual clutch, with MIL: dirt and sticking valves are cleaned, the clutches relearned, and only then the circuit traced. Thresholds are not published.

Symptoms

• Warning lamp coming and going
• Occasional harsh shift or limp mode

Most likely causes

• Loose contact or corrosion at connector or harness
• Dirt or sticking valve (dual clutch)
• Sensor or switch with dropouts
• Low fluid level, pressure drops in corners

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Read the input and output speed in live data
4. Check the connector and wiring
5. Check for other related engine codes
6. Consult the manufacturer's procedure for the transmission

Good to know

• Repair difficulty: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P0874 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 8: Transmission
• 74: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0874?

Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.

What causes code P0874?

The most common causes are: loose contact or corrosion at connector or harness; dirt or sticking valve (dual clutch); sensor or switch with dropouts.

Related codes

• P0870Transmission Fluid Pressure Sensor/Switch C Circuit
• P0871Transmission Fluid Pressure Sensor/Switch C Circuit Range/Performance
• P0872Transmission Fluid Pressure Sensor/Switch C Circuit Low
• P0873Transmission Fluid Pressure Sensor/Switch C Circuit High
• P0879Transmission Fluid Pressure Sensor/Switch D Circuit Intermittent

Sources

• static.nhtsa.gov: MC 10217091 0001
• static.nhtsa.gov: MC 10212566 9999
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.