The EGR valve plays a key role in regulating exhaust emissions and is a necessary component in countries and cities with strict emissions regulations in place. In this Real Fix the technician found an issue with the resistance of the exhaust gas recirculation valve causing the check engine list to remain on for the customer.
Vehicle
2009 Citroen C5 1.6 Diesel
Title
P1586, Replaced Exhaust Gas Recirculation Valve
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code P1586 – Power Supply To Rail Sensor, Air Mass Meter, EGR Valve: Voltage Too Low. Used the scan tool to monitor live data and found the exhaust gas recirculation valve parameter was below specifications. Disconnected the exhaust gas recirculation valve connector, visually inspected the connector and terminals and found no obvious signs of damage. With the key on, engine off, used a multi-meter to check for the presence of voltage and ground at the exhaust gas recirculation valve and found both were present. Using a lab scope, with the engine running connected to the exhaust gas recirculation valve signal wire and noticed the waveform was fixed. Used the multi-meter to measure the resistance of the exhaust gas recirculation valve with the engine off and found the measured resistance was not within specifications. This indicates the exhaust gas recirculation valve failed internally and needed to be replaced.
Correction
Replaced the exhaust gas recirculation valve, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.