P1773

What it means

P1773 on a Volkswagen means the transmission control unit has seen the signal from hydraulic pressure sensor 1 read higher than the expected or commanded pressure. It sets when the measured pressure is implausibly high, or the sensor signal is out of range, for longer than the allowed time. The layout and sensor location depend on the gearbox fitted, and on many automatic and dual-clutch units the sensor is part of the mechatronic or valve body assembly.

Symptoms

• Gearbox warning light or transmission fault message on the dash
• Harsh, jerky or abrupt gear changes
• Gearbox limp mode, often stuck in one gear
• Delayed or flared shifts
• Reduced performance or hesitation pulling away
• Gear selector or gear display flashing or showing a fault

Possible causes

• Faulty hydraulic pressure sensor or internal fault in the valve body or mechatronic unitlikely
• Pressure regulating or control valve sticking, giving genuinely excessive hydraulic pressurelikely
• Wrong, degraded or contaminated transmission fluid, or incorrect fluid levelpossible
• Wiring or connector fault between the sensor and the control unit (corrosion, chafing, poor pin contact, fluid ingress)possible
• Blocked internal filter or restricted hydraulic passage affecting pressure controlpossible
• Outdated control unit software that mishandles pressure control, where a revision is known to exist for that modelrare
• Faulty transmission control unitrare

How to diagnose

1. Scan all control units and record P1773 plus any other stored codes, then read the freeze frame data (gearbox temperature, speed, gear, load) to see when it set.
2. Check for related codes such as other pressure, solenoid, clutch or supply voltage faults, as these point towards the root cause.
3. Check the service history and confirm the correct fluid specification and the last change interval for that gearbox. Check the fluid level and condition using the model-specific procedure, as it often requires a set temperature.
4. Check battery condition and charging voltage, as low or unstable voltage can upset gearbox electronics and sensor readings.
5. Inspect the gearbox wiring and connector for damage, corrosion, fluid ingress, bent or loose pins, and carry out a wiggle test while watching live data.
6. Compare live hydraulic pressure and sensor readings against the manufacturer's specified values at idle and during a controlled test, to see if the pressure is truly high or the sensor is wrong.
7. Check for software updates or technical bulletins for the specific model and gearbox code.
8. Look for metal debris or burnt fluid in the fluid or filter to judge internal wear before replacing parts.

How to fix

• Correct the fluid level or replace the fluid and filter with the correct specification if it is old, contaminated or the wrong type.
• Repair or replace damaged wiring, terminals or the connector, and clear any fluid contamination.
• Replace the hydraulic pressure sensor if it is serviceable separately, or the valve body or mechatronic unit if the sensor is integral.
• Clean or replace sticking pressure control valves or blocked passages as the model's repair procedure allows.
• Update the transmission control unit software only where an applicable revision is known to address the fault.
• Repair or replace internal gearbox components if debris or wear is found, then perform the required adaptation or basic settings procedure.

Can I keep driving?

This code for other makes

• P1773AcuraAutomatic Transmission System Malfunction
• P1773HondaAutomatic Transmission System Malfunction
• P1773InfinitiAutomatic Transmission System Malfunction

Nearby codes

• P1772VolkswagenLoad Signal Stuck On
• P1774VolkswagenHydraulic Pressure Sensor 1 Too Low