AutoCodes – Cadillac – P0402 Cadillac

P0402 Cadillac Code - Exhaust Gas Recirculation Flow Excessive

Quick Answer

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection. 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 Cadillac indicates Exhaust Gas Recirculation Flow Excessive.
Common causes: Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection.
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 1,140

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 Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0402 Cadillac Description

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). The ECM controls the EGR valve by supplying a 12-volt pulse width modulated signal to the EGR Valve low control circuit and 12 volts to the high control circuit. The ECM monitors the EGR flow performance when the EGR is active by comparing the desired Mass Air Flow (MAF) to the actual MAF. If the difference between the desired MAF and the actual MAF is less than or greater than a calibrated threshold level the amount of detected EGR flow is out of range. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the difference between the desired mass air flow and the actual mass air flow is less than a calibrated value for greater than 12.5 s.

OBDII Code P0402 Cadillac - Exhaust Gas Recirculation Flow Excessive - AutoCodes.com — P0402 Cadillac Code - Exhaust Gas Recirculation Flow Excessive

What does this mean?

What are the Possible Causes of the DTC P0402 Cadillac?

Faulty Exhaust Gas Recirculation (EGR) Valve
EGR solenoid valve harness is open or shorted
EGR solenoid valve circuit poor electrical connection

How to Fix the DTC P0402 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 P0402 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.

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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.

Frequently Asked Questions about P0402 Cadillac Code

1. What are the common symptoms of OBDII code P0402 (Exhaust Gas Recirculation Flow Excessive) in a Cadillac?

- Common symptoms include rough idling, engine stalling, decreased fuel efficiency, and the illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P0402 in a Cadillac?

- The potential causes of code P0402 in a Cadillac can include a faulty EGR valve, clogged EGR passages, carbon buildup, or issues with the EGR pressure sensor.

3. How can I diagnose the OBDII code P0402 in my Cadillac?

- Diagnosis typically involves checking the EGR valve for proper operation, inspecting the EGR passages for blockages, and testing the EGR pressure sensor using a multimeter.

4. Can a dirty or clogged EGR valve cause code P0402 in a Cadillac?

- Yes, a dirty or clogged EGR valve can restrict the flow of exhaust gases, leading to excessive EGR flow and triggering code P0402.

5. What are some repair tips for addressing OBDII code P0402 in a Cadillac?

- Repair tips may include cleaning or replacing the EGR valve, cleaning out the EGR passages, checking the EGR pressure sensor for proper function, and ensuring all related components are in good working order.

6. Is it safe to continue driving my Cadillac with OBDII code P0402?

- While the vehicle may still be operable with code P0402, it is recommended to address the issue promptly to prevent potential damage to the engine and ensure optimal performance.

7. Can a Cadillac dealership or mechanic reset the OBDII code P0402 without fixing the underlying issue?

- While a dealership or mechanic can clear the code, it is essential to address the root cause of P0402 to prevent the problem from recurring and potentially causing further damage.

8. Are there any preventative measures to avoid OBDII code P0402 in a Cadillac?

- Regular maintenance, such as cleaning the EGR system components and using high-quality fuel, can help prevent issues leading to code P0402 in a Cadillac.

9. How long does it typically take to repair OBDII code P0402 in a Cadillac?

- The repair time can vary depending on the exact cause of the code, but it may take anywhere from a few hours to a day to diagnose and fix the issue causing code P0402.

10. Can I use an OBDII scanner to clear the P0402 code myself in a Cadillac?

- Yes, an OBDII scanner can be used to clear the P0402 code, but it is important to address the underlying problem to prevent the code from reappearing.