Engine-CodesMercury – P1405 Mercury

P1405 Mercury Code - DPF EGR Sensor Circuit High Voltage Detected

Quick Answer

The P1405 diagnostic trouble code (DTC) in a Mercury indicates that a high voltage has been detected in the Diesel Particulate Filter (DPF) Exhaust Gas Recirculation (EGR) sensor circuit. Common causes include Faulty EGR Sensor: A faulty EGR sensor can cause the circuit to detect a high voltage, triggering the P1405 code, Wiring Issues: Damaged or corroded wiring in the EGR sensor circuit can also lead to high voltage readings, Malfunctioning EGR Valve: A malfunctioning EGR valve may not be opening or closing properly, affecting the voltage in the sensor circuit. 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 EGR Sensor: A faulty EGR sensor can cause the circuit to detect a high voltage, triggering the P1405 code, Wiring Issues: Damaged or corroded wiring in the EGR sensor circuit can also lead to high voltage readings, Malfunctioning EGR Valve: A malfunctioning EGR valve may not be opening or closing properly, affecting the voltage in the sensor circuit.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1405 Mercury Description

The P1405 diagnostic trouble code (DTC) in a Mercury indicates that a high voltage has been detected in the Diesel Particulate Filter (DPF) Exhaust Gas Recirculation (EGR) sensor circuit. This code is typically found in diesel engines that are equipped with an EGR system and a DPF. The EGR system recirculates a portion of the exhaust gases back into the engine's intake manifold to reduce emissions and improve fuel efficiency. The DPF, on the other hand, traps and burns off particulate matter from the exhaust to reduce emissions.

OBDII Code P1405 Mercury - DPF EGR Sensor Circuit High Voltage Detected
P1405 Mercury Code - DPF EGR Sensor Circuit High Voltage Detected

Common Causes of P1405 Mercury

  1. Faulty EGR Sensor: A faulty EGR sensor can cause the circuit to detect a high voltage, triggering the P1405 code.
  2. Wiring Issues: Damaged or corroded wiring in the EGR sensor circuit can also lead to high voltage readings.
  3. Malfunctioning EGR Valve: A malfunctioning EGR valve may not be opening or closing properly, affecting the voltage in the sensor circuit.
  4. Clogged DPF: A clogged DPF can cause back pressure in the exhaust system, affecting the EGR sensor readings.
  5. ECM Malfunction: A malfunctioning Engine Control Module (ECM) can also cause the P1405 code to be triggered.

Symptoms of P1405 Mercury

  1. Check Engine Light: The most common symptom associated with the P1405 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Rough Idle: The engine may experience a rough idle or even stall at low speeds or when stopped.
  3. Decreased Fuel Efficiency: A high voltage in the EGR sensor circuit can lead to decreased fuel efficiency as the engine may not be operating optimally.
  4. Loss of Power: The vehicle may experience a loss of power during acceleration or when climbing hills.
  5. Increased Emissions: The vehicle may produce higher emissions than usual, which can lead to a failed emissions test.

How to Fix P1405 Mercury

  1. Diagnose the Issue: Use a scan tool to retrieve the DTC and perform a visual inspection of the EGR sensor circuit and components.
  2. Test EGR Sensor: Test the EGR sensor for proper operation and replace it if faulty.
  3. Check Wiring: Inspect the wiring in the EGR sensor circuit for damage or corrosion, and repair or replace as necessary.
  4. Test EGR Valve: Test the EGR valve for proper operation and replace it if it is malfunctioning.
  5. Clear DPF: If a clogged DPF is causing the issue, clean or replace the filter to restore proper exhaust flow.

Cost to Fix P1405 Mercury

The typical repair costs for addressing a P1405 code in a Mercury can range from $200 to $500, depending on the exact cause of the issue and the extent of the repairs needed. This estimate includes the cost of parts and labor. However, it is important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Auto repair shops commonly charge between $80 and $150 per hour for labor, with rates potentially higher in metropolitan areas or at dealerships, and lower at independent shops. It is advisable to check local rates for a more accurate estimate before proceeding with the repairs.

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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.

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