01 Unlock the Mysteries of Your Vehicle's Alternator: A Guide … • 02 Understanding and Using the Shift Lock Mechanism in Automat… • 03 The Ex-Race Engineer Tells Us The Truth About Turbo Longevi… • 04 Why Do They Ask for Your Old Car Battery? A Comprehensive G… • 05 How to Adjust and Align Your Car Headlights for Perfect Aim • 06 Airbags Get an Upgrade! ZF's Design Opens Doors for Futuris… • 07 He Paid $900 for a Used Car, Fixed It in Minutes, and Now t… • 08 The Challenges of Operating a Deep-Sea Oil Rig: Navigating … • 09 The Evolution of Engine Control Units: Then vs Now • 10 Ensuring Safety and Excellence: The Work of Experienced Nuc… •

DTC codes / P07xx · Transmission / P0749

P0749Pressure Control Solenoid 'A' Intermittent

P0749 indicates that the transmission control module has detected an intermittent fault in the pressure control solenoid 'A' circuit, which regulates hydraulic line pressure inside the automatic transmission. The computer monitors the solenoid's electrical current and response, and it sets this code when the signal drops out or behaves erratically without being continuously failed.

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 shifts, especially when the transmission is cold or under light throttle.
  • Intermittent slipping or flaring between gears as line pressure fluctuates.
  • The transmission may enter limp mode, sticking in a single gear, after the fault repeats.
  • A slight shudder or vibration during steady-speed driving when the solenoid momentarily drops out.

Common causes, most likely first

  1. Deteriorated or chafed wiring in the solenoid harness, often inside the transmission where heat and fluid exposure degrade insulation.
  2. A failing pressure control solenoid 'A' with an intermittent open or short in its internal coil.
  3. Corroded or loose pins at the transmission case connector or the transmission control module connector.
  4. Contaminated transmission fluid or a clogged solenoid screen causing erratic solenoid response.
  5. A faulty transmission control module driver circuit that cuts out under certain temperature or load conditions.
  6. Poor ground connection for the transmission control module or solenoid return circuit.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm when and under what conditions the intermittent fault sets.
  2. Inspect the transmission fluid level and condition, looking for contamination or burnt smell that could affect solenoid operation.
  3. Perform a wiggle test on the solenoid harness and connectors while watching live solenoid current data to reproduce the intermittent fault.
  4. Measure the resistance of pressure control solenoid 'A' at the transmission connector and compare it to the manufacturer's specification, checking for intermittent opens when flexing the harness.
  5. Check for continuity and voltage drop on the solenoid power and ground circuits, including the transmission control module ground, to rule out wiring faults.
  6. If electrical checks pass, remove the transmission pan and inspect the solenoid and its screen for debris, replacing the solenoid if the coil tests out of specification or the screen is clogged.
  7. After repair, clear the codes and perform a relearn or adaptation drive cycle as required, then verify the code does not return under the original freeze-frame conditions.

Intermittent faults hide in the harness

  • A wiggle test on the transmission harness while monitoring solenoid current on a scan tool often reveals a chafed wire that a static resistance check misses entirely.
  • The code can set from a momentary glitch that lasts less than a second, so the solenoid may test perfectly good by the time the vehicle reaches the shop.
  • Contaminated fluid that partially blocks the solenoid screen can cause intermittent pressure control faults without any electrical defect in the solenoid itself.
  • A poor ground at the transmission control module can mimic a failing solenoid by causing voltage spikes that the driver circuit interprets as an intermittent fault.
  • Replacing the solenoid without addressing a corroded connector pin is a common comeback, so always inspect the terminals before condemning the part.

Can I keep driving with P0749?

You can usually drive the vehicle to a repair shop, but avoid heavy acceleration or towing because erratic line pressure can cause harsh shifts and accelerated transmission wear. If the transmission enters limp mode or begins slipping severely, stop driving and arrange a tow to prevent internal damage.

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