Fuel supply restriction, such as a clogged fuel filter or blocked pick-up or lines, so the pump cannot deliver the requested quantity; Air entering the fuel system through a loose connection, perished hose or cracked line; Worn injection pump or sticking quantity adjuster that cannot achieve the demanded fuel quantity; Wiring or connector fault at the quantity adjuster or its position feedback, such as high resistance, corrosion or chafing; Worn or leaking injectors, or a fuel return fault, causing the control unit to demand more fuel than normal; Contaminated or poor-quality fuel, or water in the fuel; Fault inside the engine control unit.

P1562

Quantity Adjuster Upper Limit Attained.

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
62: FaultThe specific fault in that area

What it means

On Volkswagen diesel engines with a pump that uses a fuel quantity adjuster, P1562 means the engine control unit has driven the adjuster to its upper limit and still cannot reach the requested fuel quantity or the required fuel delivery. The control unit saw the adjuster position or duty at its maximum stop, which points to a fuel delivery shortfall, a worn or sticking adjuster, or a fault in its circuit. Exact wording and testing vary with the engine and injection pump type, so follow model-specific data.

Symptoms

Engine management warning light on
Loss of power or reduced performance, possibly limp mode
Hesitation or poor pickup under load
Rough running or uneven idle
Hard starting or occasional stalling
Increased smoke from the exhaust

Possible causes

Fuel supply restriction, such as a clogged fuel filter or blocked pick-up or lines, so the pump cannot deliver the requested quantitylikely
Air entering the fuel system through a loose connection, perished hose or cracked linelikely
Worn injection pump or sticking quantity adjuster that cannot achieve the demanded fuel quantitypossible
Wiring or connector fault at the quantity adjuster or its position feedback, such as high resistance, corrosion or chafingpossible
Worn or leaking injectors, or a fuel return fault, causing the control unit to demand more fuel than normalpossible
Contaminated or poor-quality fuel, or water in the fuelpossible
Fault inside the engine control unitrare

How to diagnose

Read all stored codes and freeze frame data, and note engine load, speed and temperature when the fault set
Check for related fuel, boost or sensor codes that might explain the extra fuel demand
Inspect the fuel filter condition, fuel lines, hoses and clips for leaks, damage or air ingress
Check the fuel for water or contamination, and drain the filter water trap if fitted
Inspect the wiring and connectors to the injection pump and quantity adjuster for damage, corrosion and poor pin tension
Using live data, compare the quantity adjuster position or duty with the requested fuel quantity at idle and under load
Check fuel supply and return flow and pressure against the manufacturer's specification for the engine
Test the adjuster circuit resistance and supply against workshop data for that specific pump type

How to fix

Replace the fuel filter and clear any blockage in the fuel supply lines or pick-up
Repair or replace leaking or perished fuel lines and seals, then bleed the system of air
Repair damaged wiring or connectors in the adjuster circuit
Replace or recondition the injection pump or quantity adjuster if testing shows it is worn or faulty
Repair or replace faulty injectors if testing shows they are the cause
Drain and refill with good-quality fuel if contamination is found

Can I keep driving?

Medium severity

The car can usually be driven for a short time to reach a workshop, but expect reduced power and possible stalling. Fix it soon, as fuel starvation or a failing pump can leave you stranded and may cause further damage.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.