P0402 code is a generic code that means “Exhaust Gas Recirculation Valve; Too much Flow Detected”. This guide is going to through what this code means, symptoms you may notice if your vehicle has this code and what it may cause to fix.
To find out everything you wanted to know about error code P0402, read our great guide below:
What is code P0402?
NOx gases that are released from the tailpipe during normal operation are a harmful pollutant that need to be controlled.
The Exhaust Gas Recirculation (EGR) system is designed to reduce harmful NOx emissions by reintroducing exhaust gases into the engine. This lowers the temperature of the combustion chamber and the amount of NOx released from the tailpipe.
P0402 sets when the Powertrain Control Module (PCM) detects that the EGR system is flowing a above calibrated amount of exhaust gases into the engine.
The PCM uses various sensors to determine if the EGR is functioning properly. It will monitor the intake manifold pressure and even the oxygen sensors to do this.
For example, by monitoring for a change in the Oxygen sensor data the PCM can detect how much flow the EGR is providing to the engine. By comparing this to what it is expected it can find a fault in the EGR valve and set code P0402.
Several symptoms are associated with the P0402 code. Even though these symptoms may vary from one model to the other. Keep in mind that a faulty EGR system can negatively impact the driving capacity of the vehicle. In extreme cases it can even cause internal engine damage. Some common warning signs of the P0402 code are:
- High fuel consumption
- Engine stalling
- Poor engine performance
- Engine pinging
- Unstable or rough idle
- Increased NOx emission can fail the emission test
- Check engine light
- Potential exhaust leaks
Causes of P0402
Due to the variations between different EGR systems, identifying and resolving a P0402 becomes pretty challenging.
Pointing out the root cause failure of this Diagnostic Trouble code can help fix it properly. First, consider the make and model of your vehicle before following any diagnostic step.
Here are some of the more common faults that may lead to a code P0402:
- Faulty EGR value
- Problem with the PCM, such as software required for the update
- Circuit faults such as poor connections, damaged or even chafing wires
- DPFE or malfunctioning EGR valve position sensor.
Simple Diagnostic Methods for the P0402 Code
Before starting any diagnosing procedure, double-check your vehicle’s manual. This ensures that the chosen troubleshooting method is appropriate for your car.
If you are not confident and do not have enough automotive knowledge or repair capabilities. Bring your vehicle to an automotive expert to fix the error.
Here are some simple things that you can check depending on equipment that you may have available:
- Use an OBD-II scan tool to check the presence of the P0402 code. Make sure if any other code is identified it is dealt with carefully
- Visually inspect all electrical connectors and vacuum hoses routed to the EGR valve. If you find any defect in vacuum hoses or electric connectors, repair or replace them
- Remove the EGR valve. If you find heavy carbon deposits around the EGR valve’s plunger, remove it with the help of a throttle body cleaner and a pipe cleaning brush
- Test the vacuum actuated EGR valve. If you find any issue in the valve’s plunger, suspect the EGR valve
- Use a bidirectional scan tool if your vehicle is equipped with an electronically actuated EGR valve to validate its operation. If there is no plunger actuation present you need to consider an EGR motor or circuit fault.
Is It Safe to Drive A Vehicle With a P0402 Code?
The sudden occurrence of the P0402 code is undoubtedly one of the severe issues because it can affect the vehicle’s drivability.
The biggest thing to realize is pinging can occur when this code is set due to recirculated exhaust gases being introduced into the combustion chamber. Pinging can lead to internal engine damage.
Please get this code repaired as soon as possible to limit the possibility of engine damage occurring.
How Much Will It Cost to Repair the P0402 Code?
Like any code that results in components that may need to be replaced, the price can vary from model to model. Here are some rough costs to replace the more common faults that may cause P0402 to set:
- EGR valve replacement -$300-$1500
- EGR wiring repair -$150-$300
- EGR Differential Pressure Sensor- $150-$250
Other Common Codes Associated with the P0402 Code
Other codes related to the P0402 excessive gas recirculation flow excessive detected are P0401, P0403, P0404, and P0405.