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Wissenscenter für Kfz-Diagnose

Fehlercode-Diagnose, Geräteauswahl und Werkstattabläufe — geschrieben von den Ingenieuren, die die Geräte entwickeln. 24 Ratgeber, monatlich aktualisiert.

Buying Guides

Best Car Diagnostic Tools for Professional Workshops in 2026

How to choose a professional scan tool in 2026: coverage, bidirectional control, programming, update cost and total cost of ownership — a buyer's checklist.

Dana Wei · 2026-10-26 · 9 Min. Lesezeit

Fehlercodes

8 Ratgeber
Fault Code Library

P0420 Code: Catalyst System Efficiency Below Threshold

P0420 means the catalytic converter is below efficiency threshold. Learn the real causes, the 6-step diagnosis, and when you actually need a new cat.

2026-10-22 · 7 Min. Lesezeit
Fault Code Library

P0171 System Too Lean Bank 1: Diagnosis Steps That Work

P0171 means the ECU has run out of fuel trim authority on bank 1. Follow this vacuum-leak-first diagnostic sequence instead of replacing parts blindly.

2026-10-22 · 6 Min. Lesezeit
Fault Code Library

P0300 Random Misfire: How to Find the Real Cylinder

P0300 means multiple cylinders are misfiring. Use misfire counters and mode 6 data to find the bad cylinder instead of replacing all ignition parts.

2026-10-23 · 7 Min. Lesezeit
Fault Code Library

U0100 Lost Communication With ECM: Wiring or Module?

U0100 means a module stopped talking to the ECM on CAN. Learn the gateway-first diagnosis, how to read bus topology, and how to avoid replacing a healthy ECU.

2026-10-23 · 7 Min. Lesezeit
Fault Code Library

P0401 EGR Flow Insufficient: Clean or Replace?

P0401 means measured EGR flow is below the commanded value. Test the valve, the passages and the sensor before choosing cleaning or replacement.

2026-10-24 · 6 Min. Lesezeit
Fault Code Library

P0299 Turbo Underboost: A Step-by-Step Diagnosis

P0299 means commanded boost is not being achieved. Check actuators, leaks and sensors in this order before condemning the turbocharger itself.

2026-10-24 · 7 Min. Lesezeit
Fault Code Library

P0087 Fuel Rail Pressure Too Low: Diesel Diagnosis Guide

P0087 on common-rail diesel: separate supply-side from regulator-side faults with rail pressure live data, then test injectors and pump in the right order.

2026-10-25 · 7 Min. Lesezeit
Fault Code Library

P0562 System Voltage Low: Battery, Alternator or Wiring?

P0562 means the ECU sees system voltage below specification. Use this test order to separate a failing battery, a weak alternator and a voltage drop in the wiring.

2026-10-25 · 6 Min. Lesezeit

Kaufratgeber

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Praxis-Anleitungen

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Vergleiche

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Regionale Märkte

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