P0749 – Pressure Control Solenoid “A” Intermittent

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: General | Location: Designator A

Definition source: SAE J2012/J2012DA (industry standard)

P0749 indicates the powertrain control system has detected an intermittent problem with Pressure Control Solenoid “A”. “Intermittent” means the fault is not present all the time; it may appear only under certain operating conditions or due to momentary electrical, hydraulic, or mechanical disruptions that affect solenoid control or the feedback the module uses to judge solenoid operation. Depending on vehicle design, the solenoid may be located inside the transmission assembly and controlled by the engine/transmission control module to manage line pressure or shift quality. Because DTC behavior and monitoring criteria vary by vehicle, confirm the exact enabling conditions, related data parameters, and test procedures in the appropriate service information before replacing parts.

What Does P0749 Mean?

P0749 – Pressure Control Solenoid “A” Intermittent means the control module has detected an intermittent condition affecting Pressure Control Solenoid “A” operation. Under SAE-style DTC structure, this is a powertrain fault that points to an on-and-off (non-continuous) issue rather than a consistently high/low electrical input or a hard open circuit. The code does not, by itself, prove the solenoid is defective; it indicates the module observed an intermittent malfunction in the solenoid control/response during monitoring. The specific strategy used to detect “intermittent” behavior (and which signals are evaluated) varies by vehicle and should be verified with service information.

Quick Reference

  • Subsystem: Transmission hydraulic pressure control; Pressure Control Solenoid “A” control circuit and solenoid operation.
  • Common triggers: Momentary loss of electrical connection, unstable power/ground to the solenoid or controller, intermittent internal solenoid fault, or intermittent hydraulic/valve behavior that makes commanded pressure control inconsistent.
  • Likely root-cause buckets: Wiring/connector faults, solenoid/actuator issues, power/ground supply problems, fluid/valve body related intermittents (varies by vehicle), control module/software (less common).
  • Severity: Moderate to high; may cause harsh/erratic shifts, reduced drivability, or protective operating modes depending on strategy.
  • First checks: Scan for companion transmission codes, review freeze-frame data, inspect harness/connectors for looseness or fluid intrusion, verify power/ground integrity with voltage-drop testing.
  • Common mistakes: Replacing the solenoid without confirming intermittent wiring/connector faults, skipping wiggle testing and road-test data logging, or ignoring fluid condition and connector contamination where applicable.

Theory of Operation

Pressure control solenoids are used to regulate transmission hydraulic pressure by varying solenoid force in response to commands from the control module. The module typically drives the solenoid in a controlled manner (often with a duty-cycled command) to achieve desired pressure control for shift timing, clutch/band apply feel, and overall drivability. Depending on design, the module may evaluate electrical behavior of the solenoid driver and/or compare commanded pressure control to inferred results using available sensors and calculated states.

For an intermittent fault, the module detects that solenoid “A” control or response is unstable: it may work normally at times and then deviate unexpectedly. Typical detections include sporadic command/feedback inconsistency, brief electrical dropouts, or erratic control behavior observed during specific operating conditions. Because the monitor logic is vehicle-specific, confirming which parameters are monitored (and under what conditions) is essential before concluding a component is faulty.

Symptoms

  • Harsh shifting: Abrupt upshifts/downshifts or inconsistent shift feel, especially when the fault occurs.
  • Shift flare: Engine speed rises unexpectedly during a shift, then the gear engages.
  • Slip sensation: Intermittent feeling of reduced drive or delayed engagement during acceleration.
  • Protective mode: Transmission may enter a reduced-function strategy that limits gear selection or alters shift scheduling.
  • Warning indicator: Malfunction indicator lamp or transmission warning message may illuminate intermittently.
  • Variable drivability: Symptoms may come and go, often tied to temperature, vibration, or specific driving conditions.

Common Causes

  • Intermittent connection at the pressure control solenoid “A” electrical connector (loose fit, corrosion, fluid intrusion, damaged lock)
  • Wiring harness intermittent open or short in the solenoid “A” control or feed circuit (chafing, pinched section, internal conductor break)
  • Poor power supply or ground integrity affecting the solenoid circuit (shared splice issues, high resistance in grounds, fuse/relay contact intermittency where applicable)
  • Pressure control solenoid “A” internal intermittent fault (coil winding intermittently open/short, sticking that causes irregular electrical response)
  • Terminal/pin issues at the control module or intermediate connector (backed-out pin, spread terminal, fretting corrosion)
  • Transmission fluid contamination or debris affecting solenoid movement enough to create intermittent control behavior (verify by testing; not confirmed by the DTC alone)
  • Valve body hydraulic sticking that causes pressure to respond inconsistently to commanded solenoid operation (verify by test; not implied by the DTC alone)
  • Control module driver or internal fault causing intermittent control of the solenoid circuit (less common; confirm only after circuit and actuator checks)

Diagnosis Steps

Tools that help: a scan tool capable of reading freeze-frame data and live transmission/solenoid PIDs, a digital multimeter, and basic back-probing/terminal tools. A wiring diagram and service information are essential because circuit routing and test points vary by vehicle. If available, a lab scope can help capture intermittent control signals, but it is not required.

  1. Confirm the DTC and capture scan data. Record freeze-frame, pending codes, and any related transmission or power supply codes. Clear codes only after data is saved so you can compare conditions on the next drive cycle.
  2. Check for obvious contributors that can create intermittent electrical behavior. Verify battery condition and charging system stability, and inspect main grounds and power distribution points that could affect the powertrain control system (do not assume they are good based on appearance alone).
  3. Review live data and commanded states. With the scan tool, monitor relevant solenoid command/feedback PIDs (availability varies by vehicle) and note whether the fault appears during specific events such as shifts, temperature changes, or vibration.
  4. Perform a targeted visual inspection of the solenoid “A” connector and harness routing. Look for damaged conduit, chafing points, sharp bends, fluid intrusion, corrosion, and evidence of prior repairs. Correct any obvious harness/connector issues before deeper electrical testing.
  5. Do an intermittent “wiggle test” while observing live data. With the engine running in a safe condition (and wheels secured as required), gently wiggle the harness and connector at the solenoid, intermediate connectors, and near the control module. Watch for sudden changes in command/feedback PIDs or for the DTC to re-set. If the symptom is reproduced, isolate the exact section that triggers it.
  6. Check connector terminal integrity. With the key off and connector disconnected, inspect for backed-out pins, spread terminals, bent pins, poor retention, or fretting. Repair terminal fit issues using approved service methods; do not rely on “tightening” pins without proper tooling.
  7. Verify solenoid circuit power/feed and ground integrity (as applicable). Using the wiring diagram, identify the solenoid feed and control/ground paths. With the circuit loaded (where service info allows), perform voltage-drop testing across power and ground paths to find high-resistance connections that may only show up under load. If load testing is not permitted by the design, use the manufacturer’s specified method.
  8. Check the solenoid coil and circuit for intermittent opens/shorts. Measure resistance at the solenoid connector and compare to service information. Then repeat the measurement while gently flexing the harness and tapping the connector body to reveal intermittent opens. If the reading fluctuates abnormally, isolate whether it’s in the harness, connector, or solenoid.
  9. Evaluate control module output to the solenoid circuit. If access and service info allow, verify that the control signal behaves consistently when the solenoid is commanded on/off. A scope can reveal dropouts or irregular drive patterns consistent with an intermittent condition. If the signal is stable at the module but unstable at the solenoid, suspect harness/connector issues.
  10. If electrical checks pass, evaluate for mechanical/hydraulic contributors that can mimic intermittent control. Follow service information for any applicable functional tests (for example, commanded actuator tests and pressure response checks, if supported). Do not replace hydraulic components without evidence from testing.
  11. After repairs, clear codes and perform a verification drive under the recorded freeze-frame conditions. Recheck for pending codes and confirm the monitor completes (as supported by the scan tool). Review live data to ensure the intermittent behavior is resolved.

Professional tip: Intermittent solenoid-related faults are often caused by terminal tension or harness strain near the transmission connector. If the code is hard to reproduce, use live-data logging during a road test and focus on reproducing the same load/shift event shown in freeze-frame; then repeat a wiggle test immediately afterward while components are still hot.

Need wiring diagrams and factory-style repair steps?

Powertrain faults often require exact wiring diagrams, connector pinouts, and guided test steps. A repair manual can help you confirm the cause before replacing parts.

Factory repair manual access for P0749

Check repair manual access

Possible Fixes & Repair Costs

Repair cost for P0749 can vary widely because the code indicates an intermittent condition that may be difficult to reproduce. Total cost depends on whether the issue is wiring/connector related, the solenoid itself, internal transmission hardware, or a control/module command problem, plus diagnostic time and labor access.

  • Repair wiring/connector faults: Clean corrosion, restore pin fit, repair chafed wiring, and secure routing to prevent vibration-related intermittents.
  • Restore power/ground integrity: Repair high-resistance feeds/grounds found by voltage-drop testing; correct loose or contaminated terminals.
  • Replace Pressure Control Solenoid “A”: Replace only after testing confirms intermittent solenoid operation or an internal electrical/mechanical fault consistent with the monitor.
  • Service valve body or hydraulic control components: If testing indicates the solenoid is commanded correctly but pressure control is erratic due to sticking/contamination (varies by vehicle design).
  • Repair harness at transmission pass-through: Address fluid intrusion, damaged seals, or connector issues where the internal and external harness interface (varies by vehicle).
  • Address fluid condition concerns: If service information supports it and inspection indicates contamination contributing to sticking/intermittency; do not treat fluid condition alone as proof of the DTC cause.
  • Control module software/module correction: Reflash/update or replace only if validated by service information and testing shows correct circuit integrity but improper command/monitoring behavior.

Can I Still Drive With P0749?

You may be able to drive short distances if the vehicle feels normal, but P0749 involves intermittent pressure control that can affect shifting and drivability without warning. Avoid heavy throttle, towing, and high-speed driving until diagnosed. If you notice harsh or slipping shifts, delayed engagement, overheating warnings, reduced-power behavior, or any safety-related warnings that affect braking or steering, do not continue driving—have the vehicle inspected or towed.

What Happens If You Ignore P0749?

Ignoring P0749 can lead to worsening shift quality, intermittent limp/backup strategies, increased heat and wear in the transmission, and a higher chance of secondary damage if pressure control becomes consistently unstable. Intermittent faults can also become harder to pinpoint over time as heat and vibration change the symptom pattern.

Compare nearby pressure solenoid trouble codes with similar definitions, fault patterns, and diagnostic paths.

  • P0799 – Pressure Control Solenoid “C” Intermittent
  • P0779 – Pressure Control Solenoid “B” Intermittent
  • P0764 – Shift Solenoid “C” Intermittent
  • P0759 – Shift Solenoid “B” Intermittent
  • P0754 – Shift Solenoid “A” Intermittent
  • P0748 – Pressure Control Solenoid “A” Electrical

Key Takeaways

  • P0749 is intermittent: The fault indicates irregular operation of Pressure Control Solenoid “A” or its control circuit behavior, not a guaranteed failed part.
  • Diagnose before replacing: Many cases trace to wiring, connectors, terminal fit, or power/ground integrity rather than the solenoid itself.
  • Reproduce and log the event: Live-data logging and a wiggle test are often necessary to catch the intermittent condition.
  • Drive with caution: Symptoms can appear suddenly; stop driving if slipping/harsh shifts or safety-related warnings occur.
  • Fix the verified cause only: Use test results to choose repairs and prevent repeat failures.

Vehicles Commonly Affected by P0749

  • Vehicles with electronically controlled automatic transmissions using pressure control solenoids for line pressure regulation
  • Higher-mileage vehicles where harness flexing, connector fretting, or terminal tension loss is more likely
  • Vehicles operated in hot conditions where heat can aggravate marginal electrical connections and solenoid performance
  • Vehicles used for towing or heavy loads that place higher demand on pressure regulation strategies
  • Stop-and-go duty cycles with frequent shifts that increase opportunities for intermittent events to be detected
  • Vehicles with prior transmission or harness repairs where routing, pin fit, or sealing may be compromised
  • Vehicles exposed to moisture or contamination near transmission connectors and underbody wiring
  • Vehicles with known charging or ground integrity issues that can destabilize solenoid control

FAQ

Does P0749 mean Pressure Control Solenoid “A” is bad?

No. P0749 means the module detected an intermittent condition related to Pressure Control Solenoid “A” operation or its control behavior. The root cause can be the solenoid, wiring/connectors, power/ground integrity, or (varies by vehicle) hydraulic control issues that make the solenoid response inconsistent.

Can low or poor electrical power cause P0749?

Yes. Marginal power or ground connections, high resistance, or unstable supply/ground paths can make solenoid control intermittent. This is why voltage-drop testing under load and checking ground integrity are important before replacing parts.

Why does the code come and go?

Intermittent DTCs often depend on temperature, vibration, harness movement, or connector contact quality. A brief open, short, or resistance change can trigger the monitor during a specific operating state and then appear normal afterward, especially after a key cycle.

Will changing transmission fluid automatically fix P0749?

Not automatically. While fluid condition can influence how hydraulic components behave, P0749 is still an intermittent solenoid-related fault entry and should be diagnosed with circuit checks and commanded-operation verification. Any fluid service should be based on service information and inspection findings, not the code alone.

What’s the best first repair attempt for P0749?

The best first step is not a repair but verification: inspect and secure the transmission connector and harness, check for corrosion or poor pin fit, and perform wiggle and voltage-drop testing while monitoring relevant live data. Then repair the specific wiring/connector, power/ground, or component fault that testing confirms.

After repairs, clear the code and confirm the fix by duplicating the conditions that previously triggered the intermittent fault and reviewing live-data logs for stable pressure control behavior.