P0749 Pressure Control Solenoid "A" Intermittent

The P0749 trouble code is an OBD-II diagnostic trouble code related to the operation of the Pressure Control Solenoid "A" in an automatic transmission.

P0749 – Pressure Control Solenoid "A" Intermittent

This code means that the Transmission Control Module (TCM) has detected an intermittent problem with the electrical or operational control of Pressure Control Solenoid "A".

Unlike a continuously present electrical fault, an intermittent P0749 condition may appear and disappear depending on factors such as vibration, transmission temperature, electrical load, wiring movement, connector condition or hydraulic conditions.

Possible causes include a failing pressure-control solenoid, damaged wiring, loose or corroded connectors, an intermittent power or ground supply, contaminated transmission fluid, a sticking valve, valve-body problems or, less commonly, a TCM fault.

It is important to understand that P0749 does not automatically mean Pressure Control Solenoid "A" needs to be replaced. The intermittent nature of the fault makes careful electrical and hydraulic diagnosis particularly important.

What Does P0749 Mean?

Automatic transmissions use pressure-control solenoids to regulate transmission-fluid pressure.

The TCM continuously adjusts solenoid operation according to conditions such as:

• Engine load

• Throttle position

• Vehicle speed

• Engine RPM

• Transmission temperature

• Selected gear

• Input shaft speed

• Output shaft speed

The basic operating process is:

TCM → Pressure Control Solenoid "A" → Hydraulic Pressure → Clutch / Brake → Transmission Operation

Pressure Control Solenoid "A" may be controlled using a variable electrical signal, commonly through pulse-width modulation (PWM), depending on the transmission design.

If the TCM detects that the solenoid's electrical or hydraulic behavior is intermittently outside the expected range, it may store:

P0749 – Pressure Control Solenoid "A" Intermittent

The exact monitoring strategy differs between manufacturers.

What Is Pressure Control Solenoid "A"?

Pressure Control Solenoid "A" is an electronically controlled hydraulic valve.

Its job is generally to regulate transmission-fluid pressure rather than directly selecting a particular gear.

The solenoid can influence:

• Line pressure

• Clutch pressure

• Shift quality

• Clutch engagement

• Torque converter operation

• Shift timing

• Transmission protection strategies

The exact function depends on the transmission.

This is why the letter "A" does not identify a universally identical component across all vehicles.

A manufacturer's hydraulic diagram should be used to determine exactly what Pressure Control Solenoid "A" controls.

What Does "Intermittent" Mean?

The word "Intermittent" is the most important part of P0749.

It means the fault is not continuously present.

For example, the transmission may operate normally when cold but develop a fault after warming up.

Alternatively, the code may appear when:

• Driving over rough roads

• Accelerating hard

• Braking

• Turning

• The transmission reaches a particular temperature

• The wiring harness moves

• Electrical voltage changes

The solenoid may work correctly for several minutes and then suddenly behave incorrectly.

This makes P0749 more difficult to diagnose than a permanent circuit failure.

Symptoms of P0749

The vehicle may experience symptoms such as:

• Check Engine Light

• Transmission warning light

• Intermittent harsh shifting

• Soft or delayed shifting

• Erratic gear changes

• Transmission slipping

• Engine RPM fluctuations

• Delayed Drive engagement

• Delayed Reverse engagement

• Transmission overheating

• Limp mode

• Reduced acceleration

• Poor fuel economy

• Changes in shift quality as transmission temperature changes

Some vehicles may show only a warning light with no obvious driving symptoms.

What Does P0749 Feel Like While Driving?

Harsh shifting

If line pressure becomes too high, gear changes may feel unusually firm.

Soft or delayed shifting

If pressure becomes too low, clutch engagement may be delayed.

Intermittent slipping

The transmission may slip only when the fault occurs.

RPM fluctuations

Incorrect hydraulic pressure can affect clutch engagement and torque transfer.

Different shift behavior when hot

A weak solenoid or contaminated valve may behave differently as transmission temperature increases.

Limp mode

If the TCM cannot reliably control transmission pressure, it may activate a fail-safe strategy.

Common Causes of P0749

Failing Pressure Control Solenoid "A"

The solenoid may have an internal electrical or mechanical fault.

Intermittent wiring problem

A partially broken wire may make and break contact as the vehicle moves.

Loose connector terminal

Vibration can cause temporary loss of electrical contact.

Corroded connector

Corrosion can create unstable electrical resistance.

Damaged transmission harness

The wiring may be damaged internally or externally.

Intermittent short circuit

A damaged wire may occasionally contact power, ground or another circuit.

Poor electrical ground

An unstable ground can affect solenoid operation.

Voltage supply problem

Unstable system voltage can interfere with solenoid control.

Contaminated transmission fluid

Debris can cause the solenoid or valve body to stick.

Sticking pressure-control valve

The hydraulic valve associated with the solenoid may not move consistently.

Worn valve body

Valve-body wear can cause pressure-control problems.

Low transmission-fluid level

Insufficient fluid can create unstable hydraulic pressure.

Incorrect transmission fluid

Incorrect fluid characteristics can affect hydraulic control.

Internal transmission wear

Worn clutches, seals or other components can produce pressure-related symptoms.

TCM problem

A control-module fault can occasionally cause intermittent solenoid control problems.

Is P0749 Serious?

P0749 should be taken seriously.

Transmission pressure is critical to proper clutch and gear operation.

If pressure intermittently becomes too high or too low, the transmission can experience:

• Harsh shifts

• Clutch slip

• Excessive heat

• Accelerated clutch wear

• Abnormal hydraulic pressure

• Additional transmission faults

However, P0749 does not automatically mean that the transmission has major internal damage.

An intermittent wiring problem or failing solenoid can produce the code.

Can You Drive With P0749?

Driving should be limited until the cause is identified.

If the transmission shifts normally and the warning light is the only symptom, driving a short distance to a repair facility may be possible.

However, avoid continued driving if you experience:

• Severe slipping

• Violent shifting

• Loss of Drive

• Loss of Reverse

• Transmission overheating

• Strong burnt-fluid smell

• Severe RPM flare

• Repeated limp-mode activation

An intermittent problem can become permanent without warning.

P0749 vs. P0745

P0745 – Pressure Control Solenoid "A" Malfunction

A general malfunction involving Pressure Control Solenoid "A".

P0749 – Pressure Control Solenoid "A" Intermittent

The problem occurs intermittently rather than continuously.

P0749 vs. P0746

P0746 – Pressure Control Solenoid "A" Performance / Stuck Off

The system detects a performance problem or a condition consistent with the solenoid being stuck OFF.

P0749 – Pressure Control Solenoid "A" Intermittent

The problem comes and goes.

P0749 vs. P0747

P0747 – Pressure Control Solenoid "A" Stuck On

The solenoid is detected as remaining active.

P0749 – Pressure Control Solenoid "A" Intermittent

The abnormal condition occurs only intermittently.

P0749 vs. P0748

P0748 – Pressure Control Solenoid "A" Electrical

The system identifies an electrical fault.

P0749 – Pressure Control Solenoid "A" Intermittent

The fault is intermittent and may involve either the electrical control or the resulting solenoid operation, depending on the manufacturer's monitoring strategy.

Where Is Pressure Control Solenoid "A"?

The location varies by transmission.

It may be:

• Inside the transmission

• Mounted in the valve body

• Under the transmission pan

• Integrated into a solenoid pack

• Part of a mechatronic unit

Some transmissions allow individual solenoid replacement.

Others require removal or servicing of the valve body or solenoid assembly.

How to Diagnose P0749

Because P0749 is an intermittent code, diagnosis should focus on finding what changes when the fault appears.

1. Scan the TCM

Retrieve all codes.

Check:

• Current codes

• Pending codes

• History codes

• Freeze-frame information

• Transmission temperature

• Commanded pressure

• Solenoid duty cycle

• Engine load

• Vehicle speed

Additional codes can provide important clues.

2. Compare multiple freeze-frame events

If the code has occurred more than once, compare the conditions.

Look for patterns involving:

• Transmission temperature

• Vehicle speed

• Engine RPM

• Throttle position

• Selected gear

• Battery voltage

If the code consistently appears at a particular temperature or during a particular shift, diagnosis becomes easier.

3. Inspect the transmission connector

Check carefully for:

• Loose terminals

• Corrosion

• Water intrusion

• Transmission-fluid contamination

• Damaged locking mechanisms

An intermittent connector problem can be extremely difficult to detect visually.

4. Inspect the wiring harness

Look for:

• Chafing

• Broken strands

• Melted insulation

• Pinched wires

• Poor previous repairs

• Harness contact with hot components

Pay special attention to areas where the harness moves or vibrates.

5. Perform a wiggle test

Where appropriate, gently move the wiring harness and connectors while monitoring the solenoid circuit.

If the signal changes or the fault appears, the harness or connector may be responsible.

This should be performed according to the manufacturer's diagnostic procedure to avoid damaging the wiring.

6. Check power and ground

Verify that the solenoid has a stable electrical supply and that the relevant ground circuit remains reliable.

7. Perform voltage-drop testing

A circuit can appear electrically connected while still having excessive resistance.

Voltage-drop testing can identify problems in:

• Wiring

• Connector terminals

• Power feeds

• Grounds

8. Monitor the solenoid control signal

If the system uses PWM control, an oscilloscope can help identify an unstable or abnormal control signal.

9. Measure solenoid resistance

Compare resistance with the manufacturer's specification.

If the resistance changes when the connector or harness is moved, an intermittent internal or wiring fault may exist.

Resistance should also be checked under appropriate temperature conditions because electrical characteristics can change with temperature.

10. Check transmission-fluid level

Verify the level using the manufacturer's specified procedure.

Some transmissions require a specific fluid temperature before the level can be measured correctly.

11. Inspect fluid condition

Look for:

• Burnt smell

• Excessive darkening

• Metal particles

• Clutch material

• Contamination

12. Monitor transmission pressure

Where applicable, compare actual hydraulic pressure with commanded pressure.

An intermittent pressure deviation can indicate a solenoid, valve-body or internal hydraulic problem.

13. Command Pressure Control Solenoid "A"

If supported by the diagnostic equipment, command different solenoid states or duty cycles and observe the transmission response.

The electrical command and hydraulic result should correspond.

14. Inspect the valve body

If the electrical circuit is good but pressure control remains inconsistent, inspect for:

• Sticking valves

• Debris

• Worn valve bores

• Restricted passages

• Internal leakage

15. Evaluate internal transmission components

If pressure control remains abnormal after the solenoid and valve body have been verified, internal wear may need to be investigated.

16. Evaluate the TCM

A TCM should be considered only after the wiring, solenoid and hydraulic system have been properly tested.

Can a Bad Pressure Control Solenoid Cause P0749?

Yes.

A solenoid can develop an intermittent internal fault that causes its electrical or hydraulic behavior to change unexpectedly.

Can Wiring Cause P0749?

Yes.

Intermittent wiring problems are particularly important with this code.

A partially broken wire or loose terminal can work normally most of the time and fail when exposed to vibration or heat.

Can a Bad Connector Cause P0749?

Yes.

A loose or corroded connector can cause intermittent loss of proper solenoid control.

Can Dirty Transmission Fluid Cause P0749?

Yes.

Contaminated fluid can cause a pressure-control solenoid or valve to stick intermittently.

Can Low Transmission Fluid Cause P0749?

Yes, potentially.

Low fluid can create unstable hydraulic pressure.

However, the fluid level should be verified before assuming it is the cause.

Can a Bad Valve Body Cause P0749?

Yes.

A sticking valve or worn valve bore can cause inconsistent pressure control even when the electrical system is functioning correctly.

Can a Bad TCM Cause P0749?

Yes, although it is generally less common.

A TCM control-driver problem can cause an intermittent command to the solenoid.

The module should be tested only after the external and internal circuits have been verified.

Can P0749 Cause Harsh Shifting?

Yes.

Excessive or unstable hydraulic pressure can produce harsh shifts.

Can P0749 Cause Transmission Slipping?

Yes.

Insufficient or unstable clutch pressure can allow clutch elements to slip.

Can P0749 Cause Limp Mode?

Yes.

The TCM may activate a fail-safe strategy if it cannot reliably regulate transmission pressure.

Can P0749 Cause Transmission Overheating?

Yes.

If the intermittent pressure problem causes repeated clutch slip, transmission temperature can rise.

Can P0749 Damage the Transmission?

Yes, if ignored.

Repeated pressure-control problems can cause:

• Clutch wear

• Excessive heat

• Fluid deterioration

• Valve-body wear

• Internal transmission damage

The risk depends on how severe and frequent the pressure-control problem is.

Common Diagnostic Mistakes With P0749

Replacing the solenoid immediately

The actual problem may be an intermittent connector or wiring fault.

Testing the vehicle only when cold

The problem may occur only after the transmission reaches operating temperature.

Ignoring wiring movement

Intermittent faults are often related to vibration or harness movement.

Checking only resistance

A resistance reading taken while the vehicle is stationary may not reveal an intermittent problem.

Ignoring voltage drop

High resistance in a connector can remain hidden during basic continuity testing.

Ignoring transmission fluid

Contaminated fluid can contribute to intermittent solenoid or valve sticking.

Replacing the valve body without testing the electrical circuit

The fault may originate in the wiring.

Replacing the TCM too early

The TCM should be the last major component considered after the circuit and hydraulic system have been tested.

Assuming the transmission needs replacement

P0749 does not automatically indicate catastrophic internal transmission failure.

What Is the Correct Repair for P0749?

The repair depends on the confirmed cause.

Possible repairs include:

• Replacing Pressure Control Solenoid "A"

• Repairing damaged wiring

• Repairing an intermittent open circuit

• Repairing a short circuit

• Replacing loose connector terminals

• Cleaning electrical corrosion

• Repairing water intrusion

• Repairing the internal transmission harness

• Correcting transmission-fluid level

• Using the correct transmission fluid

• Servicing the valve body

• Cleaning contaminated hydraulic passages

• Repairing worn valve bores

• Repairing hydraulic-pressure problems

• Updating TCM software where applicable

• Reprogramming the TCM

• Replacing the TCM if its failure is confirmed

How to Test the Vehicle After Repair

Because P0749 is intermittent, the post-repair test should reproduce the conditions under which the fault originally occurred.

Verify that:

• Solenoid "A" receives a stable control signal

• Electrical resistance remains within specification

• Power and ground remain stable

• Connector terminals remain secure

• Wiring does not lose continuity during movement

• Hydraulic pressure remains within specification

• Gear changes are smooth

• No slipping occurs

• Transmission temperature remains normal

• Limp mode does not activate

• No additional transmission codes appear

• P0749 does not return

The road test should include different temperatures, speeds, throttle positions and transmission loads.

Frequently Asked Questions About P0749

What does P0749 mean?

P0749 means the transmission control system has detected an intermittent problem involving Pressure Control Solenoid "A" or its operation.

Does P0749 mean the pressure-control solenoid is bad?

No. Wiring, connectors, fluid contamination, valve-body problems and hydraulic issues can also cause the code.

Can a loose connector cause P0749?

Yes.

Can a broken wire cause P0749?

Yes, particularly if the wire makes and breaks contact with vibration.

Can dirty transmission fluid cause P0749?

Yes. Contamination can make the solenoid or hydraulic valve stick intermittently.

Can low transmission fluid cause P0749?

Yes, potentially, because low fluid can cause unstable hydraulic pressure.

Can a bad valve body cause P0749?

Yes.

Can a bad TCM cause P0749?

Yes, although it is less common.

Can P0749 cause harsh shifting?

Yes.

Can P0749 cause transmission slipping?

Yes.

Can P0749 cause limp mode?

Yes.

Can P0749 cause transmission overheating?

Yes, particularly if pressure problems cause clutch slip.

Can I drive with P0749?

A short trip to a repair facility may be possible if the transmission is operating normally. Continued driving should be avoided if there is severe slipping, violent shifting, overheating or loss of Drive.

Does P0749 mean the transmission needs to be replaced?

No. The problem may be caused by a solenoid, connector, wiring, fluid, valve body or TCM.

Final Thoughts on P0749

P0749 – Pressure Control Solenoid "A" Intermittent indicates that the transmission control system has detected an intermittent problem with the control or operation of Pressure Control Solenoid "A".

The intermittent nature of this code is especially important. A vehicle may operate perfectly during one test drive and then develop the problem after the transmission heats up or the wiring moves.

A logical diagnostic sequence is:

Scan Tool → Freeze-Frame → Fluid Level / Condition → Connector → Wiring → Wiggle Test → Power / Ground → Voltage Drop → Solenoid Test → Hydraulic Pressure → Valve Body → Internal Transmission → TCM

The key is to determine when and under what conditions the fault occurs.

A pressure-control solenoid should not be replaced simply because P0749 is stored. If the actual cause is a loose terminal, damaged harness or sticking valve, replacing the solenoid alone will not solve the problem.

Proper diagnosis of the electrical and hydraulic systems can prevent unnecessary parts replacement and help prevent an intermittent pressure-control problem from developing into serious transmission damage.