Damage symptoms: blocked EGR valve

EGR Fault due to foreign bodies from the exhaust tract

Pierburg | Motorservice
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Information on diagnostics

What do the error messages P1444 and P16786 mean? Is the air mass sensor the problem? Why is the car jerking and what is the reason for the loss of power? Find out what causes these faults and how you can remedy the issues here.


  • Irregular engine running
  • Loss of power
  • Jerking
  • Diagnostic trouble code P1444, P16786

Foreign bodies from the catalytic converter area can be sucked through the lines of the exhaust gas recirculation due to pulsations in the exhaust tract or the vacuum in the intake air system of petrol engines. If a foreign body blocks the EGR valve in open state, exhaust gas is permanently fed back. This results in the described complaints and error messages, such as

  • P1444 position sensor EGR valve – area/function error
  • P16786 EGR – throughput too high

The fault is often attributed to the air mass sensor if less supplied fresh air is measured than is calculated for this operating state.

Damage symptoms: blocked EGR valve
Possible cause of damage: Broken pieces of the catalytic converter

These foreign bodies may be broken pieces of a damaged catalytic converter or welding beads from the catalytic converter production. Check the catalytic converter for damage, e.g. using an endoscope through the opening of the control sensor in front of the catalytic converter and replace the EGR valve.

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