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How to connect a scan tool How a P-code is built Scan tools
Enter the five-digit code your scan tool displays, or the P-code — or open the code page for your car's marque.
Look up a fault code
OBD II, model year 1996 and later: enter the P-code your scan tool displays (P0420) or the five-digit factory number (17828). Cars of 1990–1995 use the earlier system — see the Volkswagen Scan Tool Companion.
How a P-code is built — the full key
First digit — the system
- Pxxxx — powertrain
- Bxxxx — body
- Cxxxx — chassis
- Uxxxx — future systems
Second digit — who defined it
- P0xxx — Government required codes
- P1xxx — Manufacturer codes for additional emission system function; not required but reported to the government
Third digit — the subsystem
- Px1xx — measurement of air and fuel
- Px2xx — measurement of air and fuel
- Px3xx — ignition system
- Px4xx — additional emission control
- Px5xx — speed and idle regulation
- Px6xx — computer and output signals
- Px7xx — transmission
- Px8xx — transmission
- Px9xx — control modules, input and output signals
The fourth and fifth digits designate the individual components and systems.
Codes by marque
Volkswagen
Look up a code →
Audi
Look up a code →
Any make: the generic P0 codes
OBD II, 1996 and later →
Scan tools and where to get them → factory and aftermarket tools; the supplier list.
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