Engine-Codes - Mercury - P0402 Mercury

P0402 Mercury Code - Exhaust Gas Recirculation Flow Excessive Detected

- Code Popularity: 22,249 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
Table of contents
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What are the Possible Causes of the DTC P0402 Mercury?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • 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

Code Tech Notes

There is a factory service bulletin for the following Mercury models:

2000-2002 Mercury Sable
2001-2002 Mercury Cougar
2001-2002 Mercury Grand Marquis
2002-2003 Mercury Mountaineer
Mercury Factory Service Bulletin OBDII Code P0402 Code

⚠ Does your Mercury have Safety Recalls? → Check here

How to Fix the DTC P0402 Mercury?

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 pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0402 Mercury code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

High Exhaust Gas Recirculation (EGR) flow control is detected

What are Code Possible Symptoms?

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

What Does the P0402 Mercury Code Mean?

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.
P0402 Mercury Code - Exhaust Gas Recirculation Flow Excessive Detected

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