Check engine light on with 107K miles. Auto zone got P0401 code and replaced the EGR vacuum modulator valve. Light is still on. Is it best to wait a few dozen miles for light to reboot? Should I take cable off battery if light stays on?
Could be a couple of other things, read this...https://www.obd- codes.com/p0401
VSV for EGR. Fun to get to! Mounted on the back of the engine about half way up.
I seem to remember a hose coming off the Exhaust System and connecting to the bottom of that EGR Modulator. Check it out. Is the hose cracked and brittle? Is the hose plugged with carbon.
There's not enough heat coming through your egr valve to tell the computer it is working. EGR may not be opening even though you have a new modulator valve for it. Temp sensor bad, not plugged in electrically, or just insulated by too much carbon build up. Probably carbon clogged metal line from exhaust to egr valve. Clean the line first, but clean the temp sensor off at the same time.
FWL....did you ever resolve the issue with this vehicle?
Replaced EGR valve and still have engine light on after 100 miles. Also, exhaust has very strong smell, thought no smoke.
Since this EGR System is dependent on Exhaust System Back Pressure to function properly....you might consider having ...exhaust system back pressure TESTED. This is done by removing the Pre-Cat O2 sensor and installing a low PSI Gauge. Pressures more tha 2-3 PSI would indicate a possible restricted CAT.
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