AutoCodes – Cadillac – P0406 Cadillac

P0406 Cadillac Code - Exhaust Gas Recirculation Position Sensor Circuit High Voltage

Quick Answer

The Engine Control Module (ECM) uses the Exhaust Gas Recirculation (EGR) position sensor to determine the position of the EGR valve. Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0406 Cadillac indicates Exhaust Gas Recirculation Position Sensor Circuit High Voltage.
Common causes: Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, Exhaust Gas Recirculation Valve harness is open or shorted, Exhaust Gas Recirculation Valve circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 2,323

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0406 Cadillac Description

The Engine Control Module (ECM) uses the Exhaust Gas Recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5 V reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the EGR position sensor voltage is greater than 4.8 V for greater than 5 s.

OBDII Code P0406 Cadillac - Exhaust Gas Recirculation Position Sensor Circuit High Voltage - AutoCodes.com — P0406 Cadillac Code - Exhaust Gas Recirculation Position Sensor Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0406 Cadillac?

Faulty Exhaust Gas Recirculation (EGR) Valve
Exhaust Gas Recirculation Valve harness is open or shorted
Exhaust Gas Recirculation Valve circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0406 Cadillac?

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 P0406 Cadillac 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.

Need more information about the P0406 Cadillac code?

Need more information on how to fix the P0406 Cadillac code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0406 Cadillac code diagnosed by a professional: Find a repair shop in your area

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.

Frequently Asked Questions about P0406 Cadillac Code

1. What are the common symptoms of OBDII code P0406 in a Cadillac?

The common symptoms of OBDII code P0406 in a Cadillac include rough idling, engine hesitation, decreased fuel efficiency, and the illumination of the check engine light.

2. What does the OBDII code P0406 Cadillac indicate?

The OBDII code P0406 in a Cadillac indicates a fault with the Exhaust Gas Recirculation (EGR) Position Sensor Circuit, specifically a high voltage condition.

3. What are the possible causes of OBDII code P0406 in a Cadillac?

Possible causes of OBDII code P0406 in a Cadillac include a faulty EGR position sensor, a short or open circuit in the sensor wiring, carbon buildup in the EGR system, or a malfunctioning EGR valve.

4. How can I diagnose the OBDII code P0406 in my Cadillac?

To diagnose OBDII code P0406 in your Cadillac, you can use an OBDII scanner to read the code and then inspect the EGR position sensor and its wiring for any visible damage or wear.

5. Can I still drive my Cadillac with OBDII code P0406?

It is not recommended to drive your Cadillac with OBDII code P0406, as it can lead to poor engine performance and increased emissions. It is best to address the issue as soon as possible.

6. How can I repair OBDII code P0406 in my Cadillac?

To repair OBDII code P0406 in your Cadillac, you may need to replace the EGR position sensor, clean out any carbon buildup in the EGR system, or repair any damaged wiring in the sensor circuit.

7. Is it possible to reset OBDII code P0406 in a Cadillac without fixing the underlying issue?

While you can clear the code with an OBDII scanner, it is important to address the underlying issue causing OBDII code P0406 in your Cadillac to prevent further damage to the engine.

8. Can a DIY enthusiast fix OBDII code P0406 in a Cadillac?

Depending on your mechanical skills and access to tools, you may be able to fix OBDII code P0406 in your Cadillac as a DIY project by following repair guides or seeking assistance from online forums.

9. How much does it cost to repair OBDII code P0406 in a Cadillac at a professional auto repair shop?

The cost to repair OBDII code P0406 in a Cadillac at a professional auto repair shop can vary depending on the specific issue, parts needed, and labor rates, but it typically ranges from $150 to $400.

10. How often does OBDII code P0406 occur in Cadillac vehicles?

OBDII code P0406 can occur in Cadillac vehicles with EGR systems, especially in older models or those with high mileage. Regular maintenance and inspections can help prevent this code from appearing.