01 Understanding the Mass Airflow Sensor: How It Works and Its… • 02 V10 vs V8 Engine: Which One is Better? • 03 P0014 B camshaft position - timing over advanced or system … • 04 Understanding DTC "Trouble Codes" in ECU: A Complete Guide • 05 How Many Gears Are Best for Drag Racing? • 06 Drivers Are Left Stunned After Discovering The Real Purpose… • 07 This Is Why Your Car’s Door Locks Keep Flickering • 08 P0172 – System Too Rich (Bank 1): Fuel Economy Problems • 09 People Admit They Ignored This Strange Noise Until Their En… • 10 The Challenges of Operating a Deep-Sea Oil Rig: Navigating … •

DTC codes / P08xx · Transmission / P08C6

P08C6Pressure Control Solenoid M Electrical

P08C6 indicates that the transmission control module (TCM) has detected an electrical fault in the circuit for pressure control solenoid M, which is used to regulate hydraulic pressure inside the transmission. The TCM monitors the solenoid's electrical current and voltage and sets this code when the readings fall outside the expected range, indicating an open circuit, short circuit, or excessive resistance.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Harsh or delayed gear shifts
  • Transmission may enter limp mode, limiting vehicle speed and gear selection
  • Slipping or flaring during gear changes
  • Poor fuel economy or unusual engine RPM at highway speeds

Common causes, most likely first

  1. Faulty pressure control solenoid M (internal electrical failure)
  2. Damaged or corroded wiring harness or connector at the solenoid
  3. Open or short circuit in the solenoid control circuit
  4. Transmission fluid contamination or degradation causing solenoid malfunction
  5. Failing transmission control module (TCM) or internal circuit issue
  6. Loose or damaged ground connection for the solenoid circuit

How to diagnose and fix it

  1. Use a scan tool to retrieve all stored codes and freeze-frame data, then clear codes and test-drive to see if P08C6 returns.
  2. Inspect the solenoid M electrical connector and wiring for corrosion, chafing, or loose pins; repair as needed.
  3. Measure the resistance of solenoid M with a multimeter and compare to the manufacturer's specification; replace if out of range.
  4. Check the transmission fluid level and condition; service fluid if contaminated or degraded.
  5. Perform a voltage drop test on the solenoid power and ground circuits to identify excessive resistance.
  6. If the circuit and solenoid test good, diagnose the TCM and its internal drivers; replace or reprogram as required.
  7. After repairs, clear codes and verify proper operation with a road test, ensuring no pending or stored codes return.

Don't overlook the wiring harness

  • A common oversight is replacing the solenoid without checking the wiring harness for intermittent shorts that only appear when the transmission is hot or vibrating.
  • P08C6 can be set by a low battery or charging system issue that causes voltage spikes, so always verify battery and charging system health before condemning the solenoid.
  • Some vehicles use a single solenoid for multiple pressure control functions, so a failure may cause symptoms in more than one gear range, leading to misdiagnosis of a mechanical transmission problem.
  • The code may be stored as pending or history without illuminating the warning light if the fault is intermittent; always check all code statuses with a capable scan tool.
  • Aftermarket solenoids with incorrect resistance values can cause repeat codes even when new, so always compare the replacement part to the original specification.

Can I keep driving with P08C6?

If the vehicle is in limp mode or shifting harshly, avoid highway driving and seek service soon to prevent transmission damage. If only the warning light is on and the vehicle drives normally, you can drive cautiously to a repair shop, but avoid heavy loads or aggressive acceleration.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage