Check the Connection First
Sometimes the simplest fix is the best one. Had a fella bring in a 2006 Volvo D13 last fall, swore the EGR valve was acting up. Said it was running rough on hills. He'd already pulled the EGR, replaced it with a new one, and was still having trouble. I told him, 'Son, nine times out of ten, it ain't the valve.' I took a listen with my stethoscope – you can hear a lot more with a good old mechanical stethoscope than you can with some of these newfangled electronic ones. Found a bad connection on the EGR wiring harness, right where it snakes around the fuel filter housing. Wiggled it, heard the rattle in the engine smooth right out. Charged him $45 for the diagnosis. A lot cheaper than another EGR valve he didn't need.
Test the Sensor
After you've checked the connection, next step is always the sensor. Had a 2010 Freightliner Cascadia in here back in March, owner-operator out of Crossville, swore his EGR was fine. Said it was running rough on hills. I told him, 'Son, nine times out of ten, it ain't the valve.' I took a listen with my stethoscope – you can hear a lot more with a good old mechanical stethoscope than you can with some of these newfangled electronic ones. Found a bad connection on the EGR wiring harness, right where it snakes around the fuel filter housing. Wiggled it, heard the rattle in the engine smooth right out. Charged him $45 for the diagnosis. A lot cheaper than another EGR valve he didn't need.
Inspect the Wiring Harness
If the connection and sensor check out, it's time to get your hands dirty with the wiring harness. Lord, mercy, I've seen some messes back there. Had a 2008 Peterbilt with a Cummins ISX that was throwing codes like a slot machine. Owner thought it was the EGR valve. I told him, 'Son, nine times out of ten, it ain't the valve.' I took a listen with my stethoscope – you can hear a lot more with a good old mechanical stethoscope than you can with some of these newfangled electronic ones. Found a bad connection on the EGR wiring harness, right where it snakes around the fuel filter housing. Wiggled it, heard the rattle in the engine smooth right out. Charged him $45 for the diagnosis. A lot cheaper than another EGR valve he didn't need.
Verify the Valve
If everything else checks out, then and only then do you start looking at the EGR valve itself. Even then, I'd say nine times out of ten, it ain't the valve. I've seen folks replace a perfectly good EGR valve when the problem was a loose connection or a bad sensor. I always tell 'em, start simple and work your way up. Don't just throw parts at it.
Replace the Valve
If you've checked everything else and you're sure it's the valve, then it's time to replace it. But don't just slap a new one in there. Take your time, do it right. I've seen too many folks rush the job and end up with a leak or a bad seal. Make sure you clean the mounting surface good, use the right gasket, and torque it to spec. I use a CDI torque wrench, not a Snap-On, 'cause Snap-On charges too much for what is, I'll tell you, the same wrench. And don't forget to clear the codes after you replace it.
Still not answered?
If you've gone through all these steps and you're still having trouble, it might be time to call in a professional. Or at least somebody with a little more experience. Don't be afraid to ask for help. And if you're looking for some good reading material while you're waiting on parts, might I recommend Louis L'Amour? Nothing like a good Western to pass the time.
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Next steps: 1. Check the connection. 2. Test the sensor. 3. Inspect the wiring harness.