Common VAG Fault Codes for VW, Audi, Ε koda, SEAT & Cupra
A fault code tells you what a control unit has detected, not always why. This page explains the VAG fault codes we see most often at Mechalex on Audi, Volkswagen, Ε koda, SEAT and Cupra cars: what each code means, the common causes and what we check first. Search for your code, or filter by system.
Before you drive: a flashing engine warning light means a misfire bad enough to damage the catalytic converter. Ease off and stop somewhere safe. If the car is in limp mode or the gear display is flashing, drive only as far as you need to.
Not sure what your code means? Book a VAG diagnostic scan, call 0118 380 1003 or try our free VAG AI diagnosis.
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DSG gearbox fault codes
These are stored in the gearbox control unit (address 02). VAG codes are shown as they appear in VCDS. See DSG gearbox service and mechatronic repair.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| P189CVAG 006300 | Function restriction due to insufficient pressure build-up. The gearbox cannot build enough hydraulic pressure, so it limits how it works. Ross-Tech | Wiring, connections or fuses. A faulty mechatronic unit, including the hydraulic pump motor (V401). | Seen on the 7-speed DQ200 (0AM). We check the power supply at pin 9 of the 25-pin connector before condemning the mechatronic. After any repair, faults are cleared and basic settings are run. |
| P17BFVAG 006079 | Hydraulic pump overload protection. The pump keeps running but pressure is not built or held, so the mechatronic shuts it off to protect it. | DQ200 specialists most often report an internal leak, such as a cracked pressure accumulator. Low battery voltage can also set it. | Often stored with P189C. We test the battery first, then measure pressure build-up and pump run time on live data before any parts are fitted. |
| P189AVAG 006298 | Clutch 1: clearance too small. The free play on clutch K1 is below the limit. Ross-Tech | Clutch wear on the DQ200 (0AM). Volkswagen TPI 2021821 links it to judder when pulling away or at constant speed. | We confirm the clutch values on live data. The fix is a new clutch pack, followed by clutch adaptation. |
| P0841VAG 17225VAG 002113 | Transmission fluid pressure sensor/switch 1: implausible signal. Ross-Tech | Low gearbox fluid pressure. Wiring to the pressure sensor. A faulty mechatronic unit, valve body or sensor. | Fluid level and condition first, then wiring, then any Volkswagen software updates for the mechatronic. |
| P0716VAG 17100VAG 001814 | Transmission input speed sensor (G182): implausible signal. Often shows as limp mode with the engine warning light on. Ross-Tech | Wiring or connectors to the sensor. A faulty sensor. | On the 6-speed DQ250 (02E), Volkswagen notes it is often stored with P1740 (clutch temperature sensor), which usually points to wiring or connectors. |
| P1735 / P1736VAG 005941VAG 005942 | Clutch 1 (P1735) or clutch 2 (P1736) position sensor: electrical fault. | Reported by DSG specialists on the DQ381 and DQ500. The sensors are built into the mechatronic unit. Limp mode, with odd or even gears lost, is typical. | We check the wiring and connector before anything else. If the mechatronic is repaired or replaced, the clutches must be adapted afterwards. |
| P0501VAG 16885VAG 001281 | Vehicle speed sensor (G22): implausible signal. Ross-Tech | Wiring to the sensor, or between the gearbox and engine control units. On cars without a G22 sensor, the left front wheel speed sensor. | We scan the ABS module too, because a wheel speed sensor fault can set this code in the gearbox. |
Haldex all-wheel drive fault codes
These are stored in the all-wheel drive control unit (address 22). A basic OBD scanner cannot read them. See Haldex service and our VAG service intervals.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| 02248 | Valve for controlling clutch operating angle (N373): faulty. This is the Haldex coupling’s control valve. Ross-Tech | Fuses. A faulty N373 valve. | On many cars N373 is part of the Haldex control module (J492) and cannot be replaced on its own. We check the oil, filter and pump first: a blocked filter is the most common cause of Haldex pump failure we see. |
| 01324 | Control module for all-wheel drive (J492): no communications. Ross-Tech | A faulty Haldex control module. Wiring, earth points or fuses. Incorrect coding of the ABS module. | Power, earth and network wiring to the module, then ABS coding, before any module is replaced. |
EPC light and throttle fault codes
The EPC (Electronic Power Control) light comes on for faults in the electronic throttle and engine management. Power is often limited until the fault is fixed. See our guide to what causes the EPC light.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| P0120VAG 16504VAG 000288 | Throttle position sensor (G69): circuit malfunction. Ross-Tech | Mass air flow sensor (G70). Throttle position sensor. A dirty, sticking or faulty throttle actuator (V60). | Throttle body condition and the air flow sensor reading on live data. |
| P0121VAG 16505VAG 000289 | Throttle position sensor (G69): implausible signal. Ross-Tech | Wiring harness. A failed throttle body. Rarely, a failed engine control unit. | Wiring tests to the factory procedure. Some cars have a Volkswagen repair for the throttle body terminals, or a software update for cold-weather faults. |
| P0123VAG 16507VAG 000291 | Throttle position sensor (G69): signal too high. Can bring on the EPC light, a raised idle and bucking. Ross-Tech | Fuses. Wiring or connectors. A dirty or faulty throttle body. Faulty position sensors. | We clean the throttle body and run a throttle body adaptation before replacing parts. |
| P0221VAG 16605VAG 000545 | Throttle angle sensor 2 (G188): implausible signal. Ross-Tech | Wiring or connectors to the throttle body. | Live throttle data and the throttle body wiring. |
| P0562VAG 16946VAG 001378 | System voltage too low. Ross-Tech | Wiring to the control unit. A weak battery or a faulty alternator. | If it is stored in one control unit, the cause is usually local wiring. If it is stored in several at once, it points to the battery, alternator or an earth point. Intermittent codes in cold weather are common. |
Misfire, fuel and air fault codes
These are stored in the engine control unit and switch on the engine warning light.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| P0300VAG 16684VAG 000768 | Random or multiple cylinder misfire. The engine is misfiring but cannot tell which cylinder. Ross-Tech | Intake air leaks. Fuel supply or injectors. Spark plugs or ignition coils. EGR valve stuck open. Camshaft position sensor. | Air leaks, fuel pressure, plugs and coils, then compression. On direct-injection engines we check for carbon build-up on the inlet valves, which walnut blasting removes. |
| P0301 to P0304VAG 16685β16688VAG 000769β000772 | Misfire on cylinder 1, 2, 3 or 4. Ross-Tech | No spark, poor fuel delivery or low compression on that cylinder. Ignition coil, spark plug or injector. | We swap the coil to another cylinder to see if the misfire moves with it, then check the plug, injector and compression. |
| P0171VAG 16555VAG 000369 | Fuel trim bank 1: system too lean. The engine is getting too much air for the fuel it is given. Ross-Tech | A faulty mass air flow sensor. Air leaks in the intake, vacuum pipes or exhaust. | A leak check of the intake and vacuum system, then fuel pressure, fuel pump and injectors. |
| P0174VAG 16558VAG 000372 | System too lean, bank 2. Bank 2 only exists on V6 and V8 engines. Ross-Tech | Air leaks after the air flow sensor. Vacuum leaks. Fuel pressure or injector faults. A stuck EGR valve. | The same checks as P0171, on both banks. |
| P2187VAG 18619VAG 008583 | Bank 1: system too lean at idle. Ross-Tech | Leaking or blocked injectors. Air leaks after the air flow sensor. Exhaust leaks. | On the 2.0 TFSI the crankcase breather (PCV) valve is a known cause: strong vacuum at the oil filler cap at idle points to it. |
| P0101VAG 16485VAG 000257 | Mass air flow sensor (G70): implausible signal. Ross-Tech | A faulty air flow sensor. Air leaks after the sensor. A blocked air filter or catalytic converter. Corroded earth points or wiring. | Air filter and intake first, then live air flow readings. |
| P0299VAG 16683VAG 000665 | Boost pressure control range not reached. The turbo is not making the boost the engine asked for. Ross-Tech | Split or disconnected boost hoses. A faulty boost control. A faulty turbocharger or diverter valve. | Boost hoses and the diverter valve. On the 2.0 TFSI we check the N249 valve diaphragm for cracks. |
| P0087VAG 16471VAG 000135 | Fuel rail or system pressure too low. Ross-Tech | Low fuel pressure. Worn parts, such as the cam follower that drives the high-pressure pump. | Fuel pressure on live data and the low-pressure supply. On the 2.0 TFSI we inspect the cam follower and camshaft. |
| P0190VAG 16574VAG 000400 | Fuel rail pressure sensor (G247): circuit malfunction. Ross-Tech | Wiring or connections. A short to earth near the sensor. A faulty sensor. | Wiring to the sensor before replacing the sensor or pump. |
| P0191VAG 16575VAG 000401 | Fuel pressure sensor (G247): implausible signal. Ross-Tech | Fuel pressure genuinely too high or low. A low fuel level. Wiring or a faulty sensor. | On common-rail TDI engines we check for signs of high-pressure pump failure, such as metal particles in the fuel. |
Camshaft and timing fault codes
Timing codes can point to a worn chain, belt or camshaft adjuster. Get them checked promptly: a timing fault left too long can damage the engine.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| P0011VAG 16395VAG 000017 | Bank 1 intake camshaft: retard setpoint not reached (over-advanced). Ross-Tech | Camshaft adjustment valve (N205). Mechanical timing out, including the chain or belt. | The adjustment valve on output test, then the mechanical timing. |
| P0012VAG 16396VAG 000018 | Bank 1 intake camshaft: advance setpoint not reached (over-retarded). Ross-Tech | A tight, sticking or faulty intake camshaft adjuster. | Oil level and pressure, then the adjuster on output test and live data. |
| P0014VAG 16398VAG 000020 | Bank 1 exhaust camshaft: retard setpoint not reached (over-advanced). Ross-Tech | A tight, sticking or faulty exhaust camshaft adjuster. | The adjuster on output test and live data. |
| P0016VAG 16400VAG 000022 | Bank 1 camshaft position sensor (G40) and engine speed sensor (G28): incorrect correlation. The camshaft and crankshaft positions do not agree. Ross-Tech | Timing out. A camshaft adjuster problem. | The timing belt or chain and the cam timing. If it is a belt engine, see our cambelt and water pump service. |
Diesel and emissions fault codes
EGR, diesel particulate filter (DPF) and catalytic converter codes.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| P0401VAG 16785VAG 001025 | Exhaust gas recirculation (EGR): insufficient flow. Ross-Tech | A restricted or clogged EGR system. EGR valve stuck closed. Wiring to the EGR valve. | We clean or test the EGR system and valve, and check the wiring. |
| P0402VAG 16786VAG 001026 | Exhaust gas recirculation (EGR): excessive flow. Ross-Tech | EGR valve stuck open or leaking. Wiring to the EGR valve. | The EGR valve and system, and its wiring. |
| P2463VAG 18895VAG 009315 | Diesel particulate filter: excessive soot. Ross-Tech | The DPF is full. | We check the DPF and its sensors, and why it is not regenerating, before running an emergency regeneration. |
| P2002VAG 18434VAG 008194 | Particle filter bank 1: malfunction. Ross-Tech | A faulty exhaust pressure sensor (G450). A faulty DPF. | The exhaust pressure sensor first. A faulty sensor gives a wrong soot reading and stops regeneration. |
| P0420VAG 16804VAG 001056 | Catalyst system bank 1: efficiency below threshold. Ross-Tech | Intake or exhaust leaks. A faulty catalytic converter. Faulty oxygen sensors. | Leaks and the oxygen sensors before the catalytic converter is replaced. |
Control module fault codes
These can be stored in any control unit, not only the engine.
| Code | What it means | Common causes | What we check |
|---|---|---|---|
| 65535 | Internal control module memory error. Ross-Tech | Power or earth supply to the module. A faulty module, including water getting into it. | Supply and earth at the module and battery. This code usually cannot be cleared. It must not be ignored in a safety system such as airbags or ABS. |
| 16347 | Control module faulty (EEPROM error). Ross-Tech | A faulty module. Incorrect firmware. | Available software updates first, then the module itself. |
Common questions
What does the EPC light mean?
EPC stands for Electronic Power Control. It comes on when the engine control unit finds a fault in the electronic throttle or a related system, and it often limits power until the fault is fixed. It is not one fault code: the codes in the EPC and throttle section above are the usual ones behind it.
Can a weak battery cause lots of fault codes at once?
Yes. Low voltage can store codes in several control units at the same time, and it can set DSG pressure codes on the DQ200. When the same low-voltage code is in several modules, the cause is usually the battery, alternator or an earth point. We test the battery before chasing individual codes.
Why does my fault code keep coming back after it is cleared?
Clearing a code only deletes the record. If the fault is still there, the control unit stores it again. Some codes, such as 65535, cannot be cleared at all until the module is repaired.
Can I read these codes with a cheap OBD scanner?
A basic OBD scanner reads engine codes (the P-codes). Gearbox, Haldex and other module codes usually need a VAG-capable tool such as VCDS or ODIS, which we use for every diagnosis.
Code definitions are from the Ross-Tech wiki, which documents Volkswagen Group fault codes. P17BF and P1735/P1736 are not on the wiki and are as described by DSG specialists. What we check is from our own workshop. Last checked October 2026.
Got a fault code you need checked?
We read every module with ODIS and VCDS and find the cause before replacing parts. Call 0118 380 1003 or book online.
