HelpForCars.net- All Aobut Automotive Repairs
HelpForCars.net- All Aobut Automotive Repairs

P0400

P0400 - Exhaust Gas Recirculation Flow Malfunction

Comments |  Add Yours
Possible causes
- Exhaust Gas Recirculation (EGR) volume control valve stuck closed
- Faulty Exhaust Gas Recirculation (EGR) volume control solenoid valve
- Faulty EGR Valve
- Faulty EGR temperature sensor and circuit
- Exhaust Gas Recirculation (EGR) solenoid valve harness is open or shorted
- Exhaust Gas Recirculation (EGR) solenoid valve circuit poor electrical connection
- Dead (Weak) battery
Help with this
Tech notes
EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts try cleaning the EGR valve, tube and passages.
Help with this
When is the code detected?
Exhaust Gas Recirculation (EGR) flow control is not responding
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible engine hesitation
P0400 Description
Early Exhaust Gas Recirculation (EGR) systems component s include and EGR Valve, and Engine Control Μodule (ECΜ) Controlled Vacuum Switch Valve or EGR Solenoid and an EGR Vacuum Μodulator. Depending on the engine and driving conditions, the ECΜ will control the EGR Solenoid which will operate the EGR Vacuum Μodulator to regulate the opening and closing of the EGR Valve.
The EGR system on recently built vehicles uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECΜ. Two windings are turned ON and OFF in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECΜ does not issue the pulse signal. Α certain voltage signal is issued so that the valve remains at that particular opening.
Need more help?
Need parts?


HelpForCars.net OBD Codes Comments Powered by Disqus
Engine Light ON?

The Engine-Codes.com ELM327 WiFi Car Diagnostic connects to your Android phone, iPhone, iPad, or Windows computer from your vehicle.