AutoCodes - Mercedes-benz - P0408 MERCEDES-BENZ

P0408 MERCEDES-BENZ Code - Exhaust Gas Recirculation Sensor 'B' Circuit High

Repair Importance Level: 2/3
Repair Difficulty Level: 2/3
Table of contents

|P0408 MERCEDES-BENZ code possible causes

  • Faulty EGR volume control solenoid valve
  • Carbon built up on EGR valve
  • EGR volume control solenoid valve harness is open or shorted
  • EGR volume control solenoid valve circuit poor electrical connection
  • Faulty EGR temperature sensor and circuit

|How do I fix the P0408 MERCEDES-BENZ code?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|Cost of diagnosing the P0408 MERCEDES-BENZ code

Labor: 1.0

The cost of diagnosing the P0408 MERCEDES-BENZ code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|When is the P0408 MERCEDES-BENZ code detected?

An improper voltage signal is sent to ECM through the valve

|What are P0408 MERCEDES-BENZ code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine hesitation

|P0408 MERCEDES-BENZ code description

Early Exhaust Gas Recirculation (EGR) systems components include an EGR Valve, an Engine Control Module (ECΜ) Controlled Vacuum Switch Valve or EGR Solenoid, and an EGR Vacuum Modulator. Depending on the engine and driving conditions, the ECΜ will control the EGR Solenoid which will operate the EGR Vacuum Modulator 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 the 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.
OBDII Code P0408 Mercedes-benz - Exhaust Gas Recirculation Sensor 'B' Circuit High -

|Need more information with the P0408 MERCEDES-BENZ code?

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|P0408 MERCEDES-BENZ code comments

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