P1771
Load Signal Stuck Off.
- Volkswagen
- Powertrain
- Manufacturer code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 7
- AreaTransmission
- 71
- FaultThe specific fault in that area
What it means
On Volkswagen, P1771 means the load signal is stuck in the off state. This is the engine load or throttle signal the transmission control unit needs from the engine control unit to choose shift points and line pressure. The transmission control unit saw no change in that signal, or a value that did not match other inputs such as engine speed and vehicle speed, so it set the code. The signal route (a dedicated wire or the data bus) depends on the model, year and gearbox.
Symptoms
- Gearbox warning light or engine management light on
- Gearbox in emergency (limp) mode, often stuck in one gear
- Harsh, delayed or flared gear changes
- Poor or inconsistent acceleration and shift points
- Gearbox selector display flashing or showing a fault
- Fault stored alongside throttle or engine speed signal faults
Possible causes
- Damaged wiring, chafed loom or corroded connector on the load signal circuit between the engine and transmission control unitslikely
- Faulty or contaminated throttle position or accelerator pedal sensor giving the engine control unit a bad load valuepossible
- Data bus communication fault between the engine and transmission control unitspossible
- Poor power or earth supply to the transmission control unit or engine control unitpossible
- Engine-side problem affecting load calculation, such as an air leak or faulty air mass sensorpossible
- Faulty transmission control unit or engine control unitrare
- Outdated control unit software that is a known cause for the specific modelrare
How to diagnose
- Read all stored and pending codes from both the engine and transmission control units, and record the freeze frame data
- Check for related codes such as throttle, pedal, air mass, or bus communication faults and deal with those first
- Inspect the wiring and connectors between the engine and transmission control units for chafing, water ingress, corrosion and pin tension
- Check battery condition and the power and earth supplies to both control units
- View live data and compare engine load, throttle angle and engine speed between the two units while someone gently presses the accelerator
- Test the throttle or pedal sensor signal across its full range for smooth, plausible values
- Test the load signal wire for continuity, short to earth or short to supply using the wiring diagram for the exact model
- Check for manufacturer service information or software updates relevant to the vehicle and gearbox type
How to fix
- Repair or replace damaged wiring and clean or replace corroded connectors on the load signal circuit
- Replace a faulty throttle position or accelerator pedal sensor, then perform any required adaptation
- Repair the data bus fault or the cause of the communication loss
- Restore good power and earth connections to the control units
- Fix any engine fault distorting the load value, such as an air leak or faulty air mass sensor
- Replace or recode a faulty control unit, or update the software where a known fault applies, only after other causes are ruled out
Can I keep driving?
The car can usually be driven carefully to a workshop, but limp mode and harsh shifts mean it should be fixed soon. Continued driving with poor shifting can increase gearbox wear, so avoid heavy loads and hard acceleration.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.