Symptoms of a Bad or Failing EGR Vacuum Modulator

Schedule Exhaust and Emission System Inspection
Service Area

$0.00

Upfront, Transparent Price
Average rating from 127,991 customers who received a Exhaust and Emission System Inspection.

The EGR vacuum modulator is a component found on some EGR systems. It controls the flow of the EGR system by using a vacuum operated diaphragm to increase or decrease EGR flow. When the vacuum is high, combustion temperatures and airflow are naturally lower so the diaphragm will close and restrict flow, when vacuum is low airflow and combustion temperatures are higher, so EGR flow must be increased.

For vehicles equipped with them, the EGR vacuum modulator is one of the most important components of the EGR system. Any issues with it can cause the system to malfunction, which can lead to increased emissions and other problems. Usually a bad or failing EGR vacuum modulator will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

1. Engine performance issues

One of the first problems of a potential issue with the EGR vacuum modulator is engine performance issues. If the EGR vacuum modulator diaphragm tears or leaks it will disable the EGR system and may cause a vacuum leak. An excessively large vacuum leak can result in engine performance issues such as a decrease in power, acceleration, and fuel economy.

2. Check Engine Light comes on

Another symptom of a potential problem with the EGR vacuum modulator is an illuminated Check Engine Light. If the computer detects a problem with the EGR vacuum modulator signal or circuit it will set off the Check Engine Light to alert the driver of an issue. The Check Engine Light can also be activated for a variety of other reasons, so having the vehicle scanned for trouble codes is highly recommended.

3. Failed emissions test

Another symptom of a potential problem with the EGR vacuum modulator is a failed emissions test. Sometimes the EGR vacuum modulator can fail, and not set off the Check Engine Light. This will result in increased NOx emissions, which can cause the vehicle to fail an emissions test if the levels climb too high. This is particularly important for states that require emissions testing for all of their registered vehicles.

While the EGR systems on newer vehicles are being controlled by a wide variety of other methods, EGR vacuum modulators are still commonly found on many road going cars and trucks. They serve an important purpose in the overall functionality of the EGR system and when they fail can cause an increase in emissions. If you suspect that your vehicle’s EGR vacuum modulator may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic to determine if the component should be replaced.


Next Step

Schedule Exhaust and Emission System Inspection

The most popular service booked by readers of this article is Exhaust and Emission System Inspection. Yourmechanic’s technicians bring the dealership to you by performing this job at your home or office 7 days a week between 7AM-9PM. We currently cover over 10k cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Exhaust and Emission System Inspection reviews

Excellent Rating


YourMechanic Exhaust and Emission System Inspection Service

Average Rating

4.9/5

Number of Reviews

127,991

Rating Summary
119,436
4,771
955
658
2,171
119,436
4,771
955
658
2,171

ROBERT

16 years of experience
28 reviews
ROBERT
16 years of experience
Nissan Altima - Brake Pads Replacement (Front, Rear) - Atlanta, Georgia
Too Good
Isuzu Rodeo - Battery - Atlanta, Georgia
Excellent service and friendly fellow. Thanks Al

Kevo

311 years of experience
189 reviews
Kevo
311 years of experience
Chevrolet Trailblazer - Check Heating AC - Sacramento, California
Honest and efficient.Did call and let me know that he would be late due to a double booking.

Rusty

22 years of experience
379 reviews
Rusty
22 years of experience
Chevrolet Malibu - Car is not starting - Arlington, Texas
Rusty was on time and very clear as to what was going on with my car. Very positive energy

Tyrone

10 years of experience
423 reviews
Tyrone
10 years of experience
Acura TL - Starter - Fort Washington, Maryland
Tyrone was great and on time. I had a minor setback but he patiently waited while it was resolved.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE