AutoCodes – Mercury – P1405 Mercury

P1405 Mercury Code - DPF EGR Sensor Circuit High Voltage Detected

Quick Answer

The purpose of the Exhaust Gas Recirculation (EGR) system on your engine is to limit oxides of nitrogen (NOx) emissions. Common causes include Faulty Differential Pressure Feedback Electronic (DPFE) sensor (EGR pressure sensor), Plugged or damaged EGR tube, Differential Pressure Feedback Electronic (DPFE) sensor 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: P1405 Mercury indicates DPF EGR Sensor Circuit High Voltage Detected .
Common causes: Common causes include Faulty Differential Pressure Feedback Electronic (DPFE) sensor (EGR pressure sensor), Plugged or damaged EGR tube, Differential Pressure Feedback Electronic (DPFE) sensor 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.

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Code Popularity 4,915

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 19, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1405 Mercury Description

The purpose of the Exhaust Gas Recirculation (EGR) system on your engine is to limit oxides of nitrogen (NOx) emissions. This is done by redirecting small amounts of exhaust gas back through the upper intake to get mixed in with the air/fuel charge. The resultant diluted air/fuel mixture (i.e., less oxygen per cubic foot) burns cooler and combustion chamber temperatures are reduced accordingly, thereby lowering NOx emissions.
The Ford DPFE/EGR system is controlled by the Powertrain Control Module (PCM). The system employs an EGR Valve, an Electronic Vacuum Regulator (EVR), and a Delta Pressure Feedback EGR sensor (DPFE).
The DPFE Sensor measures EGR flow across an orifice located inside the special EGR Tube. The orifice is positioned between two hose ports coming off the tube which is connected to the DPFE sensor with special heat-resistant hoses. When the EGR Valve is open, a pressure differential is created across the orifice (intake manifold pressure vs. exhaust pressure). By design, this difference in pressure is measured by the DPFE sensor in terms of voltage. The DPFE voltage signal output to the PCM is directly proportional to the flow of exhaust gas entering the intake manifold.

OBDII Code P1405 Mercury - DPF EGR Sensor Circuit High Voltage Detected - AutoCodes.com — P1405 Mercury Code - DPF EGR Sensor Circuit High Voltage Detected

What does this mean?

What are the Possible Causes of the DTC P1405 Mercury?

Faulty Differential Pressure Feedback Electronic (DPFE) sensor (EGR pressure sensor)
Plugged or damaged EGR tube
Differential Pressure Feedback Electronic (DPFE) sensor harness is open or shorted
Differential Pressure Feedback Electronic (DPFE) sensor circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P1405 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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1405 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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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.