The purpose of an EGR valve is to improve your vehicle’s economy and performance.

Not only that, but it also cuts down on emissions because it allows exhaust gasses to flow back through the cylinders to get burned again.

The EGR valve even cuts down the emissions of nitrous oxide and allows the warmer exhaust to flow into the engine once again. As a result, the mixture of fuel and air won’t have to work so hard to maintain the operating temperature of the engine.

EGR Valve
EGR Valve

A faulty EGR valve should cause an ‘engine check’ light to turn on,

EGR Trouble Codes:

  • P0400….Exhaust Gas Recirculation Flow
  • P0401….Exhaust Gas Recirculation Flow Insufficient Detected
  • P0402….Exhaust Gas Recirculation Flow Excessive Detected
  • P0403….Exhaust Gas Recirculation Control Circuit
  • P0404….Exhaust Gas Recirculation Control Circuit Range/Performance
  • P0405….Exhaust Gas Recirculation Sensor ‘A’ Circuit Low
  • P0406….Exhaust Gas Recirculation Sensor ‘A’ Circuit High
  • P0407….Exhaust Gas Recirculation Sensor ‘B’ Circuit Low
  • P0408….Exhaust Gas Recirculation Sensor ‘B’ Circuit High
  • P0409….Exhaust Gas Recirculation Sensor ‘A’ Circuit


Did You Know

So, On many late model engines with Variable Valve Timing(VVT), there is no EGR valve. This is because the VVT system varies the timing of the exhaust valves to provide the same effect as EGR. This is done by changing the point at which the exhaust valves close when the engine is working hard under load. Also allowing a small amount of exhaust gas can be retained in the cylinders for the next combustion cycle.

As a result, This has the same effect on reducing combustion temperatures and NOx as recirculating exhaust gas from an exhaust port back into the intake manifold through an EGR valve. The big difference is that the VVT system can react to changing engine loads much more quickly and precisely than a traditional EGR valve. Using VVT for EGR also eliminates many of the problems associated with EGR valves such as carbon buildup and valve sticking or failure.

EGR Valve Maintenance Tips

Every 50,000 miles, you should have an air induction service done on your vehicle because it will clean the carbon and sludge that accumulates in your vehicle’s air intake system. And, of course, get regular oil changes too, because it will reduce the chances of sludge accumulating in your engine.