Audi Repair: P1400 code Audi A4, exhaust gas recirculation valve, audi a4 1996

Question
Hello!
My Audi A4 1996 2.8 could not pass emission test as "NO" was ten times higher over limit. I did diagnosis at Audi dealer which shows three Malfunctions:
Code P0116 - Engine Coolant Temperature Circuit - G62 Implausible signal
Code P1400 - Exhaust gas recirculation valve - N18 Malfunction
Code P1511 - Intake manifold change-over valve - N156 Malfunction.
Please tell me what I should fix as dealer did not want to tell me unless I agree to fix my car at dealership.
I'll be glad if you tell me where I can get a manual explaining all codes for my Audi A4 1996.
Thank you in Advance
Andy


Answer
hello
so, P0116 - means that engine module does not see coolant sensor. Most of the time module only see -40 deg. and system is trying to adjust to temperature. -40 means no communication, so you will need to replace that sensor. Very easy to replace , when car is cold. On all Audis they are located on the back of the engine ( on the coolant pipe).
P1400 - this more complicated, On the older 2 valve engines , which had EGR system , port which goes from valve to intake gets so dirty that no air/vacuum can pass to the valve. What we do is , we remove throttle body, intake manifold and try to clean that port. It takes long time but it can be done and your EGR system will work back.
this will lower NOx a lot . ( for your emission)
P1511 - I WILL just leave it alone, more like it it will go away ones you take care of the other ones. They are more important.
manual - I dont know .I will try any books with engine diag. All codes are the same on all cars , so P0116 will mean the same on BMW or ford.
good luck               pltech