Problem Description and Possible Solution
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.
Average mileage: 192,000 (145,000–230,000)
9 people reported this problem
Intermittent CEL- blocked EGR- egr flow insufficient shown on code reader
-removed EGR and inspected hole in intake manifold- it was blocked with carbon 100%-
With engine off:
held open throttle body plate with pipe on gas pedal and placed shop vac hose inside intake- be resourceful and make an adapter out of 1 inch PCV sched. 40 pipe.
Use a screwdriver/pick/awl to dig out carbon- don't be afraid to push the tool through the carbon to knock out a big piece into the intake- this is what the vacuum will pick up.
Use a round brass or steel brush to clean out the remaining carbon of the hole in the intake manifold.
I replaced the EGR valve with new to be sure of no issues, but it might be possible to clean and replace the EGR valve.
Cleaned the throttle body and intake with TB cleaner- did not require removal of intake manifold.
***Note*** Upon restart- high idle and hunting idle were encountered for some time after this repair- time was needed for the ECU to relearn idle after having much increased EGR flow and cleaned TB. NO IAC or other sensors were needed to be replaced. Be calm and patient.