Fault code P0405 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0405 – Exhaust Gas Recirculation Sensor A Circuit Low

P0405: Causes, signs and repairs

Error code P0405 is displayed and the check engine light is on - what does this mean?

DTC P0405 is triggered by the OBD system when the control unit detects a problem with the exhaust gas recirculation (EGR) valve, specifically a low voltage value in position sensor circuit A. This fault code affects the exhaust gas recirculation system, which is responsible for reducing nitrogen oxide emissions. Slight variations in the diagnosis may occur with different manufacturers, but the basic error remains the same.

What causes can this error code have?

Defective EGR valve position sensor
Damaged wiring to the EGR valve
Corroded or loose plug connections
Defective EGR valve itself
Contamination or coking of the EGR system
Faulty ground connection
Defective engine control unit (rare)

What symptoms occur in parallel with fault code P0405?

Uneven idling: The engine runs unevenly at idle speed
Reduced engine power: Noticeable loss of power while driving
Increased fuel consumption: Consumption is measurably higher than usual
Starting problems: Difficulties when starting the engine cold
Knocking noises: Metallic noises during acceleration
Exhaust problems: Increased emission values during the emissions test

How to fix the problem of error code P0405?

The repair requires a systematic approach to identify the exact cause.
Replace the EGR valve position sensor: Replace the defective sensor on the EGR valve with a new original part and calibrate it
Repair wiring: Locate damaged cables to the EGR valve, repair or replace completely
Clean plug connections: Thoroughly clean all electrical connections on the EGR system and treat with contact spray
Replace the EGR valve completely: Replace the entire EGR valve including the position sensor with a new unit
Clean the EGR system: Carry out professional cleaning of the entire EGR system with special cleaning agents
Check ground connections: Check all ground connections of the EGR system and replace if necessary

FAQ - Frequently asked questions about DTC P0405

Can I continue driving with error code P0405?

Driving is possible in the short term, but you should visit a workshop as soon as possible. Error code P0405 can lead to increased emissions and engine problems, which can get worse.

How much does it cost to repair error code P0405?

The repair costs vary between 80-400 euros, depending on the cause. A simple cleaning costs around 80-150 euros, while replacing the EGR valve can cost 200-400 euros.

How do I know if the error code P0405 has really been rectified?

After the repair, the fault memory should be deleted and a test drive carried out. If the code P0405 does not occur again after several driving cycles, the problem has been rectified.

Can I repair fault code P0405 myself?

Simple work such as cleaning the plug connections is possible, but diagnosing and replacing components requires specialist knowledge and special tools.

How often does error code P0405 occur?

DTC P0405 is a relatively common fault code, especially in vehicles with higher mileage (over 100,000 km), as the EGR system wears out due to soot and deposits.

What other fault codes occur together with P0405?

The codes P0401 (EGR flow insufficient), P0403 (EGR circuit) or P0404 (EGR area/performance) often appear at the same time, as they all affect the same system.

Vehicles in which fault code P0405 occurs most frequently

Fault code P0405 is a common EOBD fault code that indicates problems with the EGR valve position sensor and can occur on various manufacturers, but is most common on the following vehicles:

Volkswagen: Golf, Passat, Jetta, Tiguan (2005-2015)
Audi: A3, A4, A6, Q5 (2004-2014)
Ford: Focus, Fiesta, Mondeo, C-Max (2004-2016)
Opel: Astra, Corsa, Insignia, Zafira (2006-2017)
BMW: 3 Series, 5 Series, X3, X5 (2005-2015)
Mercedes-Benz: C-Class, E-Class, A-Class, B-Class (2004-2016)
Renault: Megane, Scenic, Laguna, Clio (2005-2017)
Peugeot: 307, 308, 407, 508 (2004-2016)
Citroën: C4, C5, Xsara Picasso, Berlingo (2004-2015)
Seat: Leon, Ibiza, Altea, Toledo (2005-2016)
Skoda: Octavia, Fabia, Superb, Roomster (2004-2015)
Nissan: Qashqai, X-Trail, Note, Micra (2006-2017)

If the code P0405 occurs in your vehicle, it is advisable to visit a qualified workshop as soon as possible. Early diagnosis can prevent expensive consequential damage to the engine and ensure that your vehicle complies with emissions standards. Most problems can be rectified by professional cleaning or replacing the EGR valve.

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