P0401 Mercury Monterey

We have 2005 model vehicle (about 155k miles). Just two days back we replaced the intake manifold gasket to address the leaking coolant problem. They had to mill the manifold too saying it ate away part of the manifold. Today the check engine light came up and this is the code detected. Could this be related to the above fix? Before taking it back to the shop is there something I could checkout and also how to approach the shop if it goes on to something else?
Thanks for your feedback,

No, its not related but you need to check if the EGR valve was put back when they did the work.
Read the following…it describes what this code means


Thanks for reply. Is this visible under the hood. What to look for?
Also in the attached image you can see a plastic box resting on I believe is alternator. It looks like it is broken from a bracket. Any idea what is it and do it need to be fixed to front wall (maybe duck tape it for now)?

The EGR valve is attached to the intake manifold so the problem may have been caused during the repair. The EGR valve is located near the throttle body with a 1" pipe connected to it from below, inspect to see if it is damaged or disconnected.

EGR means “exhaust gas recirculation”. It’s used to cool the cylinders a little during accelerations, going uphill etc (for emissions and engine life) opening a valve (the egr valve) to allow some exhaust gas into the intake manifold. There’s vacuum and electrical signals used to control when the egr valve opens, and by how much. The engine computer can tell if enough exhaust flow is entering the intake manifold. The code is saying the computer is turning the egr valve on, but not noticing enough flow into the intake manifold.

  • egr valve faulty
  • vacuum signal faulty or disconnected
  • electrical signal faulty or what it controls isn’t working (check dpfe gadget)
  • exhaust manifold path isn’t connected to egr valve inlet, or that path is blocked (by gasket material, etc)