Diagnostic Fault Finding
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Exhaust Gas Recirculation Valve (EGR)

So what is an EGR and why is it causing problems?

The EGR (Exhaust gas recirculation) valve directs exhaust gas back into the inlet manifold and is controlled by the engine control module.

The EGR or (Exhaust Gas Recirculation Valve) directs exhaust gas back into the inlet manifold and is controlled by the engine control module. The idea behind the EGR is purely emissions related. More oxygen into the cylinder = more power and better fuel economy, more oxygen combined with high combustion temperatures = increased nitric oxide and nitrogen dioxide (NOX). So energy and fuel efficiency is traded for NOX levels. The other downside is that as the exhaust gas passes back into the inlet, it mixes with air that contains oil vapour from the PCV (positive crankcase ventilation). The hot exhaust gas bakes the oil which creates carbon. The excessive carbon eventually cokes up the inlet manifold and often damages or restricts the manifold pressure sensor and worse case scenario; We have seen damage to valves and injectors on one bank of a TDV8. The EGR was permanently stuck open causing one side of the engine to run hot and rough to the point where it was excessively damaged.

What are the symptoms of a failing EGR (Exhaust Gas Recirculation) valve?

Symptoms could be Rough Idling, Fuel Detonation Noise, Increase in Emission of Nox Gases or Overall Erratic Engine Functioning.


There are many different ways an EGR valve can fail on a vehicle, and many factors that can affect the EGR valve The most common cause can be a clogged or restricted EGR passageway created by carbon build up over time or Carbon build up on an EGR temperature sensor. With sensor it could be an electrical fault also.

The DPFE (Differential Pressure Feedback Sensor) or hoses that lead to the EGR valve, blocked or faulty.

A clogged DPF (Diesel Particulate Filter) or Catalytic Converter

Electrical problems with the EGR valve control circuit

Vacuum operated EGR valves having Vacuum supply issues (leaking)

so you can see they are many parts that can go wrong and do and this is not all of them.

Auto Code has years of experience in Auto Fault Finding diagnostics, DPF (Diesel Particulate Filters) deletes, EGR Deletes, ECU Re-mapping and performance tuning on all makes of Vehicles, especially European cars and commercial vehicles. We have the highest quality performance tuning solutions for all most vehicles, ensuring the best driving experience, while consistently providing customer satisfaction. If you love driving your vehicle, why not try an Auto Code Performance tune. You can expect to save 5-20% in fuel depending on your tune type and the way you drive. It’s up to you how far you would like to take your performance tune-up, and if you are not happy with the tune, we can always put your vehicle back to standard. If you need more information regarding your car, please contact us by email or phone 0457 060 808. We are happy to talk to you about your vehicle.



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Custom Performance Tuning:

Give your engine the very best, with an Auto Code custom tune. Your Auto Code custom tune will give you the benefit of increased Power, Torque, improved derivability and the added bonus of enhanced fuel economy

  • No loose boxes and wiring in the engine compartment
  • Boost pressure and air flow is optimised not tricked.
  • On board computer shows correct fuel consumption
  • Anti skid program (ESP) function is fully retained
  • Regeneration emptying of diesel particle filter (DPF) is retained
  • Correct calculation of exhaust temperature
  • Correct calculation of service interval
  • The diagnostic system and all adaptive features are retained
  • No enlarged NOx, HC, CO, CO2, Soot emissions compared with original
  • Correct calculation of exhaust temperature
You will be left wondering why it wasn't done at the factory.
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