P1561
Quantity Adjuster Deviation.
- Volkswagen
- Powertrain
- Manufacturer code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 61
- FaultThe specific fault in that area
What it means
On Volkswagen, P1561 means 'Quantity Adjuster Deviation'. The engine control unit has seen that the actual position of the fuel quantity adjuster differs from the position it commanded. It is mainly associated with diesel engines that have a pump-mounted fuel quantity adjuster, and the exact setup depends on the model and engine.
Symptoms
- Engine management light on
- Reduced power or limp-mode behaviour
- Poor or uneven running, or hesitation under load
- Hard starting or intermittent stalling
- Excess smoke or higher fuel consumption
Possible causes
- Wiring or connector fault between the control unit and the injection pump or quantity adjuster (corrosion, chafing, high resistance)likely
- Faulty quantity adjuster or its position sensor, usually inside the injection pumplikely
- Fuel supply problem such as a blocked filter, air in the fuel or a restricted line, which affects pump behaviourpossible
- Low battery voltage or a poor earth or supply to the pump or control unitpossible
- Worn or sticking internal injection pump componentspossible
- Fault in the engine or pump control unitrare
How to diagnose
- Read all stored codes and freeze frame data, and note any related codes for the pump, fuel temperature or sensors that may point to a common cause.
- Check battery condition and charging voltage, and check the main earths and supply feeds.
- Inspect the wiring and connectors at the injection pump and control unit for damage, corrosion, chafing, moisture or loose pins.
- Inspect the fuel filter, fuel lines and connections for air ingress, leaks or restriction, and check the fuel supply to the pump.
- Compare the commanded and actual quantity adjuster values in live data, at idle and under load, if your scan tool shows them.
- Test the wiring for continuity, short circuits and resistance, following the wiring diagram for that model and engine.
- Check the quantity adjuster and position sensor values against the manufacturer's specification, using the model-specific procedure.
- Clear the code after the repair and road test to confirm it does not return.
How to fix
- Repair or replace damaged wiring, connectors or terminals.
- Replace the fuel filter, fix any air leaks and clear fuel restrictions.
- Restore battery condition and repair poor earths or supply faults.
- Replace or overhaul the injection pump or quantity adjuster where the tests show it is faulty, and carry out any required adaption or basic setting for that model.
- Replace or reprogram the control unit only if it is confirmed faulty, or if the manufacturer lists an outdated calibration as a known cause.
Can I keep driving?
Medium severity
The car may run in limp mode and could stall, so avoid long journeys and heavy loads, and book a diagnosis soon. Stop driving if it stalls repeatedly or loses power in traffic.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.