Code p0400 for check engine light - 1996 Chevrolet Impala SS

code p0400 refers to exhaust gas recirculation(EGR) system---flow malfunction.===causes---hose leak/blockage--basic setting not carried out (if applicable)---wiring---EGR valve ---EGR solenoid---ECM
check out the valve and solenoid.

EGR malfunction. Check the vacuum hose to the EGR valve first.

P0400 (EGR flow malfunction), P1333 Make sure about this code its a chevy code so you will need to recheck,If anything the EGR is stuck open.Or you are dealing with a vacuum leak causing rough idle

A code P0400 may mean that one or more of the following has happened:
• Plugged EGR passage which restricts the flow of exhaust gasses
• Faulty EGR solenoid
• Faulty EGR solenoid wiring/harness
• Vacuum lines damaged/disconnected to the EGR valve solenoid or to the EGR valve
• Faulty EGR valve

After you have made the repairs go back to Advance Auto and have them remove this stored trouble code .Most places will remove them from your computer for free.

Hi

Refer to this link for answer
http://www.obd-codes.com/p0400

the code p0400 is not a fuel leak but a lack of the fuel tank to hold a vaccum. it is possibly one of three things : abad cap :a bad evap solenoid : a bad canister dump valve. most of these would need to be check by a tech to determin which one.
the ets is usualy an abs problem with the lite on it should turn the abs off

P0400 is auxillary emmisions control and P0500 is vehicle speed idle speed control auxiliary inputs.

the passage that causes this low flow is in the intake, it gets full of carbon and gunk, try running a wire through it, also make sure the EGR passes a functional test.

P00A0 is a factory readable only code (i.e. only ford dealers have the computer to read it)
the P0400 is a generic E.G.R. flow restriction code. so yes a dvom (multimeter) and a vacuum pump to diagnose it correctly, also check for loose wires as ford harness connectors are known to fail alot due to crappy phenolic content in the plastic and heat combined they can warp and / or corrode the contacts