P0746 Code: Pressure Control Solenoid A Performance or Stuck Off

What the P0746 code means

An automatic transmission does not engage gears with levers but with hydraulic pressure. Packs of clutches apply and release depending on the pressure they receive, and a solenoid controlled by the computer regulates that pressure.

The adjustment is fine. Too much pressure applies the clutches all at once and the shift feels harsh, with a clear jerk. Too little pressure applies them slowly and they slip, which creates heat and wear.

The P0746 code is stored when that solenoid does not regulate the way it should or is stuck. Unlike P0745, which flags the electrical circuit, this is a performance code: the solenoid receives the command, but the hydraulic result does not match.

That widens the list of causes beyond the solenoid itself. Degraded fluid or fluid with particles, a worn valve body or a saturated filter produce the same effect, because what fails is not the command but the hydraulics that have to carry it out.

Keep in mind that on most modern transmissions pressure is not measured directly. The computer infers it from the current it sends to the solenoid and from the behavior it sees in engine speed during the shift. That means the code can be set by a drifting indirect reading, not only by a truly wrong pressure. An input or output speed sensor with an imprecise signal throws off that calculation and produces a pressure code with the hydraulics in good shape.

Make a note of whether the shifts get better or worse once the fluid is hot, because that separates two very different scenarios. If they improve as it warms up, it points to degraded fluid or fluid of the wrong viscosity, which flows poorly when cold. If they get worse as it warms up, it points to internal wear: with hot, thinner fluid, the internal leaks in the valve body or the seals grow and the pressure drops.

P0746 code symptoms

• Harsh shifts with a clear jerk, or slow shifts with slipping.
• Check engine light and transmission warning light on.
• Engine rpm that rises without the vehicle accelerating in proportion.
• Transmission in limp mode, stuck in one gear.
• Higher fluid temperature.
• Shifts that get better with hot fluid and worse when cold, or the other way around.
• Burning smell coming from the transmission.
• Shifts that clearly get better or worse depending on the fluid temperature.

Likely causes of the P0746 code

1. Degraded fluid, fluid with particles or fluid of the wrong specification. Always the first check.
2. Wrong fluid level, either too high or too low.
3. Pressure control solenoid stuck by particles or internal wear.
4. Worn valve body, with internal pressure leaks.
5. Saturated transmission filter.
6. Worn transmission pump.
7. Leaking pass-through connector, which contaminates the outer harness.
8. Worn internal clutches that no longer respond to the correct pressure.
9. Outdated module software.
10. Hardened internal seals, whose leaks grow with hot, thinner fluid.

How to diagnose the P0746 code step by step

1. Check the fluid level and condition following the manufacturer procedure, which on many vehicles calls for a warm engine that is running.
2. Look at the color and smell. Clear red means healthy fluid. Dark brown with a burnt smell means confirmed internal wear.
3. Look for metal particles in the fluid or in the pan. Finding them shapes the whole repair.
4. Read all the codes in the transmission module, because codes for a specific solenoid narrow the diagnosis a lot.
5. Compare the commanded pressure with the actual pressure in live data if the vehicle reports it.
6. Find out whether the problem affects one gear or all of them. A single gear points to its hydraulic circuit. All gears point to line pressure.
7. Measure the solenoid resistance at the outer connector.
8. Check the fluid temperature during sustained driving.
9. Note whether the shifts get better or worse as it warms up. Better points to the wrong fluid. Worse points to internal wear with pressure leaks.

How to fix the P0746 code

• Change the fluid and filter with the exact manufacturer specification if they are degraded.
• Correct the fluid level following the vehicle procedure, neither too high nor too low.
• Replace the pressure control solenoid if its resistance is out of range or it does not respond.
• Clean or replace the valve body when the diagnosis points to it.
• Replace the pass-through connector if fluid is leaking into the harness.
• Update the module software if the manufacturer released a revision.
• Consider a rebuild if there are plenty of metal particles and confirmed slipping.
• Put the fluid change first if the symptoms improve when hot, and plan an internal inspection if they get worse.

Replacing the solenoid in a transmission with contaminated fluid sets the repair up to fail again: the particles will attack the new part too.

Technical reference data

• Typical pressure control solenoid resistance: 3 to 15 ohms depending on the type.
• Normal fluid temperature: 70 to 100 °C (158 to 212 °F).
• Typical line pressure: 4 to 18 bar (about 58 to 261 psi) depending on the gear and the load.
• Healthy fluid is clear red with no smell. Degraded fluid is dark brown with a burnt smell.
• A problem in one gear points to the hydraulic circuit of that gear. In all gears, it points to line pressure.
• Symptoms that improve when hot point to unsuitable fluid. Symptoms that get worse point to internal pressure leaks.

Brand-specific notes

Fluid type is not interchangeable between manufacturers. Each specification has friction properties calculated for that particular transmission, and filling it with a universal fluid produces harsh shifts and pressure codes without any part being bad.

Before you plan an internal repair, check whether a software update exists for the module. Several manufacturers have corrected pressure strategies that way, and it is far cheaper than opening the transmission.

Frequently asked questions about P0746