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DTC codes / P09xx · Transmission / P0968

P0968Pressure Control Solenoid 'C' Control Circuit/Open

P0968 indicates that the transmission control module (TCM) has detected an open circuit or excessive resistance in the control circuit for pressure control solenoid 'C', which is one of the hydraulic pressure regulators inside the automatic transmission. The TCM commands a specific current to the solenoid and monitors the resulting voltage or current feedback; when the circuit does not respond as expected, it stores this code and typically illuminates the malfunction indicator lamp.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning lamp, often with no other noticeable symptoms
  • Harsh or delayed gear engagements, especially when shifting from park to drive or reverse
  • Erratic shift timing or slipping during acceleration as line pressure control degrades
  • Transmission may enter limp mode, limiting operation to a single gear or fixed pressure strategy
  • Rough downshifts or torque converter clutch apply shudder under light throttle

Common causes, most likely first

  1. Damaged, chafed, or disconnected wiring in the solenoid 'C' control circuit, particularly at the transmission connector or along the harness
  2. Corroded or loose electrical terminals at the solenoid, the internal transmission connector, or the TCM
  3. Open winding or internal failure of pressure control solenoid 'C' itself
  4. Failed transmission control module (TCM) driver circuit for solenoid 'C'
  5. Contaminated transmission fluid causing solenoid valve sticking and abnormal current draw
  6. Internal transmission mechanical wear that alters hydraulic pressure and overloads the solenoid circuit

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related transmission codes or pending faults before clearing anything
  2. Inspect the transmission wiring harness and connector for chafing, corrosion, or loose pins, and repair as needed
  3. Measure the resistance of solenoid 'C' at the transmission connector and compare it to the manufacturer's specification
  4. Check the control circuit for continuity and short-to-ground or short-to-power faults between the TCM and the solenoid
  5. If the circuit tests good, command the solenoid with a bidirectional scan tool and observe current and pressure response
  6. Replace pressure control solenoid 'C' if it fails electrical or functional testing, following the manufacturer's service procedure
  7. After repair, clear codes, perform a transmission adaptive relearn if required, and road test to confirm the fault does not return

What the code does not always mean

  • A P0968 does not automatically condemn the solenoid; a corroded connector pin or a chafed wire in the harness is a frequent cause that costs far less to fix.
  • Some vehicles set this code only when the transmission fluid is cold or at a specific temperature, so a full cold-to-hot drive cycle may be needed to reproduce the fault.
  • A weak battery or charging system fault can cause the TCM to misreport solenoid circuit codes, so always verify system voltage before chasing the transmission.
  • After solenoid replacement, many transmissions require an adaptive relearn or clutch fill procedure; skipping it can leave harsh shifts that mimic a recurring fault.
  • Internal transmission debris from a failing clutch pack can clog the solenoid valve body and set a circuit code even when the solenoid's electrical winding tests good.

Can I keep driving with P0968?

You can usually drive the vehicle to a repair shop if the transmission still shifts and the warning light is the only symptom, but avoid heavy throttle, towing, or long highway trips because degraded line pressure can cause clutch slip and internal damage. If the transmission is in limp mode or slipping noticeably, stop driving and arrange a tow to prevent further mechanical failure.

Tools that help

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

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