P0402 GMC Code - Exhaust Gas Recirculation Flow Excessive
Quick Answer
The P0402 diagnostic trouble code for GMC vehicles indicates that there is an excessive flow of exhaust gas recirculation (EGR) into the intake system. Common causes include Malfunctioning EGR valve, Clogged EGR passages, Faulty 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 GMC indicates Exhaust Gas Recirculation Flow Excessive.
- Common causes
- Common causes include Malfunctioning EGR valve, Clogged EGR passages, Faulty 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 GMC Description
The P0402 diagnostic trouble code for GMC vehicles indicates that there is an excessive flow of exhaust gas recirculation (EGR) into the intake system. The EGR system is responsible for recirculating a portion of the exhaust gases back into the engine's intake manifold, which helps reduce nitrogen oxide emissions. When the EGR flow is excessive, it can lead to a variety of issues that can affect the vehicle's performance and emissions.
Common Causes of P0402 GMC
- Malfunctioning EGR valve
- Clogged EGR passages
- Faulty EGR temperature sensor
- Issues with the EGR solenoid
- Carbon buildup in the EGR system
Symptoms of P0402 GMC
- Rough idle or engine misfires
- Loss of power or acceleration
- Decreased fuel efficiency
- Check Engine Light illuminated
- Failed emissions test
How to Fix P0402 GMC
- Diagnose the issue by using a scan tool to confirm the P0402 code and inspecting the EGR system components for any visible damage or clogs.
- Clean or replace the EGR valve if it is found to be faulty. This involves removing the valve, cleaning it thoroughly, or replacing it with a new one.
- Check and clean the EGR passages to ensure there are no blockages hindering the flow of exhaust gases.
- Test the EGR temperature sensor and EGR solenoid to determine if they are functioning correctly. Replace any faulty components as necessary.
- Clear the diagnostic trouble code from the vehicle's computer and test drive the vehicle to ensure the issue has been resolved.
Cost to Fix P0402 GMC
The cost of repairing a P0402 code on a GMC vehicle can vary depending on the specific cause of the issue and the labor rates in your area. On average, you can expect to pay between $200 and $500 for parts and labor to address this problem. However, costs may be higher if additional components need to be replaced or if the issue requires more extensive repairs. It's recommended to consult with a trusted mechanic or auto repair shop to get an accurate estimate based on your vehicle's make and model. Keep in mind that labor rates at auto repair shops can vary, so it's a good idea to shop around for the best price.
Need more information about the P0402 GMC code?
Need more information on how to fix the P0402 GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0402 GMC code diagnosed by a professional: Find a repair shop in your area
Information for Specific GMC Models
- P0402 2014 GMC Sierra — Exhaust Gas Recirculation Flow Excessive
- P0402 2015 GMC Sierra — Exhaust Gas Recirculation Flow Excessive
- P0402 2016 GMC Sierra — Exhaust Gas Recirculation Flow Excessive
- P0402 2017 GMC Sierra — Exhaust Gas Recirculation Flow Excessive
- P0402 2018 GMC Sierra — Exhaust Gas Recirculation Flow Excessive
Frequently Asked Questions about P0402 GMC Code
1. What are the common symptoms of OBDII code P0402 GMC?
The common symptoms of code P0402 GMC include a Check Engine light illumination, rough idling, reduced fuel efficiency, and potentially an increase in emissions.
2. What are the possible causes of OBDII code P0402 GMC?
The excessive Exhaust Gas Recirculation (EGR) flow indicated by code P0402 GMC can be caused by a faulty EGR valve, clogged EGR passages, a malfunctioning EGR temperature sensor, or issues with the EGR vacuum modulator.
3. How can I diagnose the cause of OBDII code P0402 GMC?
To diagnose the cause of code P0402 GMC, it is recommended to perform a visual inspection of the EGR system components, check for vacuum leaks, test the EGR valve functionality, and use a scan tool to monitor EGR system data.
4. Can a dirty or clogged EGR valve trigger code P0402 GMC?
Yes, a dirty or clogged EGR valve can disrupt the proper flow of exhaust gases and trigger code P0402 GMC. Regular maintenance and cleaning of the EGR valve can help prevent this issue.
5. Is it safe to continue driving with OBDII code P0402 GMC present?
While it may be possible to drive with code P0402 GMC present, it is not recommended as the underlying issue causing the excessive EGR flow can lead to further engine problems if left unresolved.
6. How can I repair OBDII code P0402 GMC?
Repairing code P0402 GMC typically involves cleaning or replacing the EGR valve, clearing any blockages in the EGR passages, checking and replacing the EGR temperature sensor if necessary, and ensuring proper operation of the EGR vacuum modulator.
7. Can a malfunctioning EGR temperature sensor cause code P0402 GMC?
Yes, a malfunctioning EGR temperature sensor can cause code P0402 GMC by providing incorrect temperature readings to the engine control module, leading to improper EGR flow calculations.
8. What are some tips to prevent OBDII code P0402 GMC from recurring?
To prevent code P0402 GMC from recurring, it is advisable to regularly inspect and clean the EGR system components, use high-quality fuel to reduce carbon buildup, and address any engine performance issues promptly.
9. Will resetting the Check Engine light resolve OBDII code P0402 GMC?
Resetting the Check Engine light may temporarily clear the code, but it will not fix the underlying issue causing code P0402 GMC. It is important to diagnose and repair the root cause to prevent the code from reappearing.
10. Can a failing EGR vacuum modulator trigger code P0402 GMC?
Yes, a failing EGR vacuum modulator can disrupt the vacuum signal to the EGR valve, leading to improper EGR flow and triggering code P0402 GMC. Inspecting and replacing the EGR vacuum modulator can help resolve this issue.
Discuss the causes and fixes for P0402 GMC OBDII Code
Code P0402 GMC 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.