The EGR System tends to get restricted or blocked with carbon after 100,000- 125,000 miles which will cause an emissions test failure for NOX. If the EGR system is equipped with an EGR temperature sensor it will trigger a Check Engine Light for improper EGR flow. The repair is to clean out the EGR passages and the EGR Temperature sensor. Our technicians tell this repair is pretty straight forward and takes about 1-1.5 hours. It is also wise to verify the EGR system components i.e. the Transducer, EGR Valve and VSV Solenoid at this time.Google+
Car Problem Reports
Toyota Corolla Failed Emissions Test Due to Blocked EGR System
Toyota Corolla Problem
Average Mileage: 198,332 mi (135,000 mi - 267,000 mi)
Engine Code P0401 showed up on my scanner. Just needed to replace the Vacuum Control Module. Cheap and easy. Love my car!
Visitor, 1996 Toyota Corolla, 191,524 mi
egr restricted flow replaced all components
Visitor, 1995 Toyota Corolla, 207,017 mi
Check engine light turned on. EGR valve completely clogged. Cleaned valve and reset engine light.