P08CA: Pressure Control Solenoid M Control Circuit Low

GM sets this code on the Corvette's Tremec dual clutch for a short to ground in the circuit of synchronizer actuation valve 1, which serves the odd-gear shaft. The test runs while the low-side driver is switched on: the sense pin should then sit at a defined level, and if the driver chip reports it below about 1.7 V (±0.5 V), a ground short is assumed. Confirmation takes 150 ms at 8.75 to 18 V battery voltage with the engine not cranking, and the check is suspended when P0882 or P0883 is present. Type A, MIL at once, monitored continuously. Valves 2 to 5 have their own low codes (P27BF onwards). The driver should expect a fallback mode until the wiring fault is repaired.

Symptoms

• Check engine light on immediately
• Fallback mode with restricted gears

Most likely causes

• Control wire chafed through to ground
• Shorted turns in the solenoid coil
• Fluid in the transmission connector

What to check, in order

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

1. Check the fluid level and condition according to the manufacturer
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Check the transmission connector
4. Read the data with a transmission-compatible scanner
5. Measure the solenoid valve circuit
6. Leave opening the transmission to a specialized repair shop

Good to know

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

What each character of P08CA means

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

Frequently asked questions

Can I keep driving with code P08CA?

Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.

What causes code P08CA?

The most common causes are: control wire chafed through to ground; shorted turns in the solenoid coil; fluid in the transmission connector.

Related codes

• P08C3Pressure Control Solenoid M
• P08C8Pressure Control Solenoid M Control Circuit/Open
• P08C9Pressure Control Solenoid M Control Circuit Range/Performance
• P08CBPressure Control Solenoid M Control Circuit High
• P08C1Pressure Control Solenoid L Control Circuit Low
• P27BFPressure Control Solenoid N Control Circuit Low

Sources

• gsi.ext.gm.com: 25OBDG07A Part 1
• gsi.ext.gm.com: 23OBDG07
• 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.