P0402 Mercury 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 Mercury 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 Mercury 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 Mercury?
- 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 Mercury?
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.
Code Tech Notes
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
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0402 Mercury 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.
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Frequently Asked Questions about P0402 Mercury Code
What does the OBDII code P0402 mean for a Mercury vehicle?
P0402 indicates that the Exhaust Gas Recirculation (EGR) system is allowing more exhaust gas back into the intake manifold than it should, causing excessive flow.
What are the common symptoms of code P0402 in a Mercury?
Symptoms may include a Check Engine Light, rough idling, poor acceleration, reduced fuel efficiency, and increased emissions.
What causes the P0402 code in Mercury vehicles?
Common causes include a stuck-open EGR valve, clogged EGR passages, a faulty EGR position sensor, or issues with the EGR control solenoid.
Can a faulty EGR valve trigger the P0402 code?
Yes, a malfunctioning EGR valve, especially if stuck open, is one of the most common causes of the P0402 code.
Is it safe to drive a Mercury with a P0402 code?
While it may be safe to drive short distances, prolonged driving with this code can lead to engine performance issues and potential damage to the catalytic converter.
How can I diagnose the P0402 code on my Mercury?
Start by inspecting the EGR valve, EGR passages, and associated vacuum lines for blockages or damage. Use a scan tool to check EGR system data and test the EGR valve operation.
What repairs are typically needed for a P0402 code?
Repairs may include cleaning or replacing the EGR valve, clearing clogged EGR passages, replacing a faulty EGR position sensor, or fixing any damaged vacuum lines or wiring.
Can a vacuum leak cause the P0402 code?
Yes, a vacuum leak affecting the EGR system can lead to excessive exhaust gas flow and trigger the P0402 code.
How much does it cost to fix the P0402 code on a Mercury?
Repair costs can range from $100 to $500 or more, depending on the specific issue, such as cleaning the EGR valve or replacing faulty components.
Can I fix the P0402 code myself?
If you’re experienced with car repairs, you can clean the EGR valve, inspect passages, and check vacuum lines. However, more advanced diagnostics may require professional help.
Discuss the causes and fixes for P0402 Mercury OBDII Code
-
After changing out the DPFE ,checking the EGR valve with vacuum and cleaning the intake manifold cavity,I noticed the cat on that side was getting really hot.Perhaps the cat is blocked forcing exhaust gases thru the EGR valve causing the excess flow code to set....Hopefully I will be able to confirm this after the blockage in the cat is repaired.
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