P0874 moderate

Transmission Fluid Pressure Sensor/Switch C Circuit Intermittent

The P0874 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch C Circuit Intermittent. This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: hard
Estimated cost: $100 - $500 (parts and labor)

Check Your Fluid First

ANCEL AD310 OBD-II Scanner

Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.

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Read Transmission Codes

LAUNCH CRP123X (Reads All Systems)

Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.

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Common Symptoms

Check Engine Light illuminated intermittently
Occasional harsh or soft shifts
Sporadic limp mode
Inconsistent transmission behavior between drives

Probable Causes (Ranked by Likelihood)

Loose connector at pressure sensor C Very High
Intermittent wiring fault from vibration or heat High
Failing pressure sensor C with intermittent output Moderate
Intermittent internal hydraulic pressure fluctuation Low

Step-by-Step Diagnostic Procedure

Perform a wiggle test on the sensor C connector while monitoring live data
Inspect wiring for chafing near hot exhaust components
Data-log sensor C readings over multiple drive cycles
Check for manufacturer TSBs on intermittent sensor C issues

Frequently Asked Questions

Why does the code only appear sometimes?

Intermittent faults are often caused by loose connectors, chafed wires, or sensors that fail under certain temperature or vibration conditions.

Can heat from the exhaust cause intermittent sensor faults?

Yes, exhaust heat can degrade wiring insulation over time, causing intermittent shorts or opens that only occur when the vehicle is at operating temperature.

Should I replace the sensor or fix the wiring?

Always check the wiring and connector first. If those are in good condition, the sensor may have an internal intermittent fault and should be replaced.