P1738

What the Code Means

Code P1738 points to a fault in the control circuit for oil pressure control solenoid C. This solenoid meters hydraulic pressure to engage a specific clutch pack in the automatic transmission. The transmission control unit (TCU) detected an electrical fault — an open circuit, a short, or a failed solenoid. The solenoid has to work correctly for shifts to be smooth and on time.

Symptoms

• Harsh shifts — jolts when changing gears
• Slipping — the engine revs without acceleration
• Delayed engagement — a pause after selecting D or R
• Check Engine light — comes on in the instrument cluster

Diagnosis and Repair

Step 1: Check Solenoid Resistance

• Disconnect the solenoid connector and measure resistance with a multimeter.
• Normal value: 4–6 ohms. Anything outside that range points to a fault.

Step 2: Inspect the Wiring and Connector

• Check the wires for continuity, corrosion, and damaged contacts.
• Make sure the connector is seated and free of contamination.

Step 3: Replace the Solenoid

• If resistance is out of spec or the wiring checks out, replace the solenoid.
• OEM part number: 24001442383.

Step 4: Clear Codes and Test Drive

• After the repair, clear the fault codes and take a test drive to verify.

Secondary Problems

Ignoring P1738 leads to incorrect pressure in the hydraulic system. That causes clutch slip, overheating, and accelerated wear. In advanced cases the transmission can fail completely, requiring a rebuild or a replacement unit. Replacing the solenoid on time prevents expensive consequences.