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 an open state, exhaust gas is permanently fed back into the intake air. In a technical post, Pierburg detailed what the symptoms and possible cause are for this EGR fault.

• Irregular engine running
• Loss of power
• Jerking
• Diagnostic trouble codes P1444 (position sensor EGR valve – area/function error) and/or P16786 (EGR – throughput too high)

These faults are often attributed to a faulty air mass sensor, if less supplied fresh air is measured than is calculated for this operating state.

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, 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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