P0405 Code: EGR Sensor A Circuit Low – Causes, Symptoms & Fixes with ICARZONE UR800 Scanner

September 11, 2025

Table of Contents 1. What is P0405? 2. Common Causes 3. Key Symptoms 4. Models Prone 5. Diagnostic Steps with ICARZONE UR800 6. Fixes 7. Repair Costs 8. Prevention 9. FAQ 10. Summary

Diagnostic Guide

P0405: Exhaust Gas Recirculation Sensor A Circuit Low

Understand the causes, symptoms, and repair steps for P0405 EGR sensor circuit low in Ford, Chevrolet, and Volkswagen models. Diagnose with the ICARZONE UR800 scanner.

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P0405

1. What is P0405?

P0405 means the EGR (Exhaust Gas Recirculation) Sensor A reports a voltage lower than expected. This sensor monitors EGR valve position. A low signal usually indicates wiring faults, sensor failure, or ECM issues.

2. Common Causes

Faulty EGR position sensor
Corroded or loose connectors
Short to ground in sensor wiring
Carbon buildup restricting EGR valve
ECM calibration error (rare in VW Jetta & Ford Escape)

3. Key Symptoms

Check Engine Light with stored P0405
Poor acceleration & reduced fuel economy
Rough idle or stalling
Failed emissions test

4. Models Prone to P0405

Ford: Escape 2.5L, Fusion 2.0L EcoBoost
Chevrolet: Malibu 1.5L Turbo, Cruze 1.4L
Volkswagen: Jetta 1.4T, Passat 2.0T

5. Diagnostic Steps with ICARZONE UR800

The ICARZONE UR800 can read live EGR sensor voltage, helping confirm if the issue is wiring, sensor, or ECM.

6. Fixes

Replace faulty EGR sensor with OEM part
Repair damaged wiring & connectors
Clean carbon deposits from EGR valve
Update ECM software if applicable

7. Repair Costs

EGR Sensor: $80–$200
Wiring repair: $50–$120
ECM update: $0–$50
Labor: $100–$200

8. Prevention

Inspect EGR wiring every 20k miles
Clean EGR valve during intake service
Use UR800 scanner for periodic monitoring

9. Frequently Asked Questions

Can I drive with P0405?Short trips are possible but fuel economy and emissions will suffer. Fix as soon as possible.

Does UR800 help fix P0405?Yes, it shows live EGR sensor data and confirms circuit voltage.

10. Summary

The P0405 code indicates low voltage from the EGR Sensor A circuit. With ICARZONE UR800, you can quickly confirm if the issue is wiring, sensor, or ECM. Timely repair restores performance and prevents failed emissions.