The Quick Answer above is the generic definition. What follows is the model-specific detail for the Volkswagen models that log P0408.
DTC/P0408·Volkswagen
P0408 on Volkswagen: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Volkswagen
P0408 on a Volkswagen means EGR position sensor 'B' is sending a voltage above its normal operating range. Sensor B only exists on engines with a second EGR valve or a second EGR circuit, such as diesels that combine high-pressure and low-pressure EGR. The fault is usually an open signal wire, a missing ground, or a sensor that has failed internally.
Typical repair cost, all makes€70 - €730
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Volkswagen Golf
2013-2024The EA288 TDI in the Golf 7 and later uses two EGR circuits: a conventional high-pressure EGR valve and a low-pressure EGR system that takes exhaust gas after the particulate filter. Each has its own valve and position feedback, so a sensor B code is possible on this four-cylinder diesel. Read the fault with manufacturer-level software (VCDS or ODIS), which names the valve concerned, before ordering parts, and have the EGR adaptation carried out afterwards.
What causes P0408 on a Volkswagen?
Beyond the generic causes listed on the main P0408 page, these are the patterns noted for Volkswagen models:
Volkswagen GolfOpen circuit or broken pin in the wiring to the second EGR valve
Volkswagen GolfFailed position sensor in the second EGR valve
How to diagnose P0408 on a Volkswagen with OBD2
Follow these steps to pinpoint the root cause of P0408:
- Identify which physical valve or sensor is 'B' in the manufacturer's service data. On engines with high- and low-pressure EGR it belongs to one of the two circuits, and manufacturer-level software names it directly
- Back-probe sensor B signal wire. Reading near 5V with key on indicates an open signal or sensor failed open
- Verify sensor B ground at the connector. Missing ground will let the signal float high
- Inspect for loose connector locks, especially after recent intake or turbo service
- If signal stays high with the connector fully seated and ground confirmed, replace the integrated valve or sensor assembly, then have the EGR adaptation carried out with manufacturer-level software
How much does P0408 cost to fix on a Volkswagen? (EUR)
Estimated repair costs for P0408 in EUR, compiled across makes. Expect Volkswagen parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0408
These codes are often seen alongside P0408 or point to related issues, on any make:
Looking for the full P0408 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0408 guideSkanyx · Volkswagen
Diagnose P0408 on your Volkswagen
Your car logged P0408. Skanyx reads it on any standard Bluetooth OBD2 adapter, tells you whether it is safe to keep driving, and shows the €70-€730 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.
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