Sticking or internally worn fuel quantity adjuster on the injection pump; Contaminated or degraded diesel fuel causing varnish and deposits on the adjuster; Faulty wiring or corroded connector at the quantity adjuster solenoid; Restricted fuel supply, such as a clogged fuel filter or weak lift pump; Air ingress into the fuel system from deteriorated seals or lines; Engine control module software calibration issue or internal fault; Mechanical wear inside the distributor-type injection pump affecting adjuster travel

DTC codes / Volkswagen codes / P1563

P1563 · VolkswagenQuantity Adjuster Lower Limit Attained

Q: What does code P1563 mean?

Quantity Adjuster Lower Limit Attained. P1563 on Volkswagen diesel engines means the engine control module (ECM) has detected that the fuel quantity adjuster has reached its lower mechanical or electrical limit. The ECM commands a certain injected fuel quantity but the adjuster cannot move any further toward the 'less fuel' direction, so the actual quantity deviates from the requested value beyond the allowed threshold.

P1563 on Volkswagen diesel engines means the engine control module (ECM) has detected that the fuel quantity adjuster has reached its lower mechanical or electrical limit. The ECM commands a certain injected fuel quantity but the adjuster cannot move any further toward the 'less fuel' direction, so the actual quantity deviates from the requested value beyond the allowed threshold.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyProfessional

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or engine stumble when the quantity adjuster is near its limit
Reduced engine power or limp mode under certain load conditions
Hard starting or stalling after the engine is warm
Excessive smoke or poor fuel economy in some cases
Intermittent hesitation during acceleration

Common causes, most likely first

Sticking or internally worn fuel quantity adjuster on the injection pump
Contaminated or degraded diesel fuel causing varnish and deposits on the adjuster
Faulty wiring or corroded connector at the quantity adjuster solenoid
Restricted fuel supply, such as a clogged fuel filter or weak lift pump
Air ingress into the fuel system from deteriorated seals or lines
Engine control module software calibration issue or internal fault
Mechanical wear inside the distributor-type injection pump affecting adjuster travel

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm when the lower limit was attained
Inspect the quantity adjuster connector and wiring for corrosion, chafing, or loose pins
Check fuel quality and replace the fuel filter if contamination or restriction is suspected
Perform a fuel system pressure and delivery test to rule out supply-side problems
Run the manufacturer's quantity adjuster adaptation or basic setting procedure with a capable scan tool
Remove and clean the quantity adjuster, then retest; replace it if cleaning does not restore full travel
If the adjuster and wiring are good, evaluate the injection pump for internal wear or replace the pump

What most technicians miss on P1563

A low fuel level or a nearly empty tank can cause the quantity adjuster to hit its lower limit temporarily, setting a false P1563 that clears after refueling.
The quantity adjuster is often blamed when the real problem is a restricted fuel return line, which raises internal pump pressure and forces the adjuster toward its lower stop.
On some Volkswagen diesel engines, a weak battery or poor ground can cause the ECM to misread the adjuster position, so always verify voltage and grounds before condemning the pump.
After replacing or cleaning the quantity adjuster, the ECM must relearn its end stops; skipping the adaptation procedure will set P1563 again immediately.
P1563 can be stored by a completely different fault, such as a faulty coolant temperature sensor, because the ECM uses that signal to calculate expected fuel quantity.

Can I keep driving with P1563?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, towing, or long trips because the engine may enter limp mode without warning. If the engine runs roughly or stalls, stop driving and arrange a tow.

Tools that help

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Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.