P0402 2018 GMC Sierra Code - Exhaust Gas Recirculation Flow Excessive
Quick Answer
The P0402 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that there is excessive flow detected in the Exhaust Gas Recirculation (EGR) system. Common causes include Faulty EGR valve, Clogged EGR passage, Malfunctioning EGR temperature sensor. 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 2018 GMC Sierra indicates Exhaust Gas Recirculation Flow Excessive.
- Common causes
- Common causes include Faulty EGR valve, Clogged EGR passage, Malfunctioning EGR temperature sensor.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code P0402 2018 GMC Sierra Description
The P0402 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that there is excessive flow detected in the Exhaust Gas Recirculation (EGR) system. The EGR system is responsible for recirculating a portion of the exhaust gases back into the engine's intake manifold to reduce nitrogen oxide emissions. When the EGR flow is excessive, it can lead to a variety of performance issues in the vehicle.
Common Causes of P0402 2018 GMC Sierra
- Faulty EGR valve
- Clogged EGR passage
- Malfunctioning EGR temperature sensor
- EGR vacuum control solenoid issue
- Carbon buildup in the EGR system
Symptoms of P0402 2018 GMC Sierra
- Check Engine Light illuminated
- Rough idling or engine stalling
- Reduced fuel efficiency
- Increased emissions
- Engine misfires
How to Fix P0402 2018 GMC Sierra
- Diagnose the specific cause of the excessive EGR flow by using a scan tool to retrieve the DTC and perform further testing on the EGR system components.
- Inspect and clean the EGR valve and passage to ensure proper flow of exhaust gases.
- Test the EGR temperature sensor and replace if necessary.
- Check the EGR vacuum control solenoid for proper operation and replace if faulty.
- Clear the DTC and test drive the vehicle to ensure the issue has been resolved.
Cost to Fix P0402 2018 GMC Sierra
The cost of repairing a P0402 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue. On average, the parts for this repair can range from $100 to $300, while the labor costs can range from $150 to $400. Keep in mind that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and the shop's labor rates. It's recommended to consult with a trusted mechanic or auto repair shop for a more accurate cost estimate.
Need more information about the P0402 2018 GMC Sierra code?
Need more information on how to fix the P0402 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0402 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P0402 2018 GMC Sierra Code
1. What does the OBDII code P0402 mean for a 2018 GMC Sierra?
P0402 indicates that the Exhaust Gas Recirculation (EGR) system is detecting an excessive flow of exhaust gases being recirculated into the intake manifold, which is outside the expected range.
2. What are the symptoms of code P0402 on a 2018 GMC Sierra?
Common symptoms include rough idling, decreased fuel efficiency, poor engine performance, hesitation during acceleration, and the Check Engine Light illuminating.
3. What causes the P0402 code to trigger on a 2018 GMC Sierra?
Possible causes include a stuck-open EGR valve, carbon buildup in the EGR system, a malfunctioning EGR sensor, a faulty EGR solenoid, or a damaged EGR valve gasket.
4. Can a vacuum leak cause the P0402 code on my GMC Sierra?
Yes, a vacuum leak in the EGR system can lead to excessive exhaust gas flow, potentially triggering the P0402 code.
5. How do I fix the P0402 code on a 2018 GMC Sierra?
Common fixes include cleaning or replacing the EGR valve, checking and repairing vacuum lines, replacing the EGR sensor or solenoid, and clearing carbon buildup in the EGR passages.
6. Is it safe to drive with a P0402 code on my GMC Sierra?
Driving with the P0402 code may not cause immediate damage, but it can lead to reduced engine performance, higher emissions, and potential long-term damage if left unresolved.
7. How much does it cost to repair a P0402 code on a 2018 GMC Sierra?
Repair costs depend on the specific issue but typically range from $150 to $400, including parts and labor for cleaning or replacing the EGR valve or related components.
8. Can a dirty air filter cause the P0402 code on a GMC Sierra?
While unlikely, a severely clogged air filter could impact engine performance and exacerbate EGR system issues, contributing to the code.
9. How do I diagnose the P0402 code on a 2018 GMC Sierra?
Diagnosis involves scanning for additional codes, inspecting the EGR valve and related components for damage or carbon buildup, checking vacuum lines, and verifying the EGR sensor's functionality.
10. Will clearing the P0402 code fix the problem on my GMC Sierra?
Clearing the code will turn off the Check Engine Light temporarily, but it will likely reappear unless the underlying issue with the EGR system is resolved.
Discuss the causes and fixes for P0402 2018 GMC Sierra OBDII Code
Code P0402 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.