DIAGNOSTIC TROUBLE CODE (DTC) P0400

EXHAUST GAS RECIRCULATION OUT OF LIMIT

Features of the Circuit

• By any chance if high combustion temperatures are created by oxides of nitrogen then An Exhaust Gas Re-circulation (EGR) system which is the chief feature of this system will be boosted to counter this.
• This is done by supplying small amounts of exhaust gases back into the combustion chamber.
• Combustion temperatures are minimized as soon as the air/ fuel mixture dilutes the exhaust gases.
• The EGR valve has been specially designed to generate exhaust gases to the engine without using intake manifold vacuum.
•  This valve regulates exhaust flow entering the intake manifold from the exhaust manifold through an orifice with an ECM controlled pintle.
• The pintle position is monitored by the ECM using inputs from the Throttle Position (TP) and the Manifold Absolute Pressure (MAP) sensor.
• This task over, the ECM then directs the EGR valve to operate as necessary by controlling an ignition signal through the ECM.
• The ECM further monitors the results of its command through a feedback signal.
• The desired EGR position can be checked with the help of a scan tool.
• A voltage signal representing the EGR valve pintle position is sent to the ECM by a 5 volt reference and a ground to the EGR valve.
• The scan tool can also be used here to note the feedback signal which is the actual position of the EGR pintle.
• The correct EGR position should always be close to the commanded or Desired EGR position.
• This Diagnostic Trouble Code (DTC) is capable of identifying an open or short circuit.