P0402 Mercedes-Benz Code - Exhaust Gas Recirculation Flow Excessive Detected
Quick Answer
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. Common causes include EGR volume control valve stuck open, Faulty EGR volume control valve, EGR solenoid valve harness is open or shorted. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
- What it means
- P0402 Mercedes-Benz indicates Exhaust Gas Recirculation Flow Excessive Detected.
- Common causes
- Common causes include EGR volume control valve stuck open, Faulty EGR volume control valve, EGR solenoid valve harness is open or shorted.
- Severity
- Moderate - service should be scheduled soon.
- Can I drive?
- The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Code P0402 Mercedes-Benz Description
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.
What are the Possible Causes of the DTC P0402 Mercedes-Benz?
- EGR volume control valve stuck open
- Faulty EGR volume control valve
- EGR solenoid valve harness is open or shorted
- EGR solenoid valve circuit poor electrical connection
- Faulty EGR temperature sensor and circuit
How to Fix the DTC P0402 Mercedes-Benz?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0402 Mercedes-Benz code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0402 Mercedes-Benz code?
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Frequently Asked Questions about P0402 Mercedes-Benz Code
1. What are the common symptoms of OBDII code P0402 in a Mercedes-Benz?
- Common symptoms include rough idling, reduced fuel efficiency, engine hesitation, and potentially a Check Engine Light.
2. What causes the OBDII code P0402 in a Mercedes-Benz?
- The most common causes are a faulty EGR valve, clogged EGR passages, a malfunctioning EGR temperature sensor, or a problem with the EGR solenoid.
3. How can I diagnose the OBDII code P0402 in my Mercedes-Benz?
- Diagnosis typically involves checking the EGR valve and related components for proper operation, inspecting for carbon buildup in the EGR passages, and testing the EGR system sensors.
4. Can I drive my Mercedes-Benz with OBDII code P0402?
- It is generally not recommended to drive with this code as it can lead to decreased engine performance and potential damage over time. It's best to address the issue promptly.
5. Is it safe to ignore the OBDII code P0402 in my Mercedes-Benz?
- Ignoring this code can lead to further damage to the engine and emissions system. It's best to address the underlying issue to prevent more significant problems.
6. How much does it typically cost to repair OBDII code P0402 in a Mercedes-Benz?
- The cost of repair can vary depending on the specific cause of the code, but it may range from $200 to $600, including parts and labor.
7. Can I repair the OBDII code P0402 in my Mercedes-Benz myself?
- DIY repair is possible for those with automotive repair experience and the necessary tools. However, it's recommended to consult a professional if you're unsure about the repair process.
8. How long does it typically take to repair OBDII code P0402 in a Mercedes-Benz?
- The repair time can vary depending on the cause of the code and the complexity of the repair needed. It may take anywhere from 1 to 3 hours to complete the repair.
9. Will OBDII code P0402 cause my Mercedes-Benz to fail an emissions test?
- Yes, this code indicates an issue with the EGR system, which is essential for emissions control. It's likely that your vehicle will fail an emissions test with this code present.
10. Can a Mercedes-Benz dealership help me with the OBDII code P0402?
- Yes, Mercedes-Benz dealerships have trained technicians and specialized equipment to diagnose and repair OBDII codes like P0402. It's recommended to consult a dealership for professional assistance.
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