What is a exhaust gas recirculaton on the motor of a pickup?

My dad has a pickup year is in the 90's. I can't remember if it is a ford or chevy. But the 'service motor soon' light has been on for a few months. Well, I took it to AutoZone to have it checked. The code was: PO401. It said… Too little flow on the EGR or blocked passage or failed EGR valve.

What is that and where on the motor is it located? He has been driving it for 2 months with the light on. He moved into assisted living center 3 months and it has been parked. I have it now and would like to drive it to see my daughter's. Will it be safe to drive 128 highway miles wihout breaking down?

If the egr valve or attached pipe gets clogged with carbon, it can cause rough idling, hard starting, and sometimes even no start. If its a Ford, its normally bolted to the egr spacer(spacer located between throttle body and upper intake)or directly behind the upper intake.A Ford Ranger has a pipe attached that connects between the egr valve and exhaust manifold.A F150 may have a egr spacer like listed above. The egr valve also has a small vacuum hose attached to it and a evp sensor mounted to it.Too little egr flow is usually a sign for a carbon clogged valve passage or a clogged egr tube.Carbon that builds up in the egr system will become hard and crusty totally stopping flow.Remove the egr valve, use carb cleaner to clean its passages and use the same for the pipe if it exists. There's also a evr solenoid that sends vacuum to the egr. If this solenoid is defective, the egr won't receive a proper amount of vacuum, meaning the egr valve won't open fully.

EGR = exhaust gas recirculation. At higher RPMS the valve routes exhaust gas back to the intake manifold to reduce combustion temps and reduce the formation of NOx--the main component of smog. Not fixing it can cause excessive combustion temps, knock, and engine damage. Get a shop manual for this car and follow the instructions on how to replace the valve.

Vehicles did not come with EGR until sometime in the 70's and if it is running fine then no need to bother with it unless you need to get a smog check where you live. An older vehicle may well have a buildup of carbon plugging the passage in the intake manifold running to it and not surprisingly often a real pain to reach to clean out and may need to remove the manifold to do it.

If I'm changing an EGR valve on a car I'm not familiar with then I just follow the tubes on the intake manifold until I find it. Some are in plain sight and some can be a pain and have to remove it and install the new one only by feel.

If you have to ask that, then your better off taking it to a mechanic.