There is smoke coming from under my hood and a funny smell

Today after i got my oil changed and pertol refilled, my Service Engine Soon light stays ON. I got the code from an auto shop as "P0400-Exhaust gas air flow". How to fix this? I checked the petrol tank cap also. It is closed properly.

cut out once at an intersection was rough starting then just fine - trip meters reset - only time this has happened so far

i start it back but it hesitate to crank and then when I start driving it will shut off again

Car loses power and skips while driving, dropping to 10-15 mph before regaining power. The problem is always worse in the morning when the car is cold. The check engine light has not come on.

i change the relays

Just recently when fueling my vehicle it won't start . it takes a few time I hold the pedal to start never done this before ..m Please help my only reliable vehicle

55,02senser b1×1 po325,aux emmision p1448,bank112 po 140 what does all this mean and are there ways to get my check engine light off and is it on because of all these codes

At speeds over 55 is whines and at slower speeds it growls. This just started. The car only has 97000 miles on it and I bought it used.

when i turn on the car the idle goes down to number 1 then up again and then it stays between the 1 and 2. When im parked the idle stays in between the 1 and 2 . Is there anyway i can fix this problem? tHERE IS NO LIGHT ENGINE ON OR NOTHING, I ALSO TOOK THE CAR TO AUTO ZONE AND THE GUY PUT THE CODE MACHINE TO TEST IT AND NOTHING AS WELL...

Two days ago I replaced the front passenger side strut/shock assembly on my '01 nissan altima which, up until then, the car started up like clockwork. When I went to test drive vehicle upon completion of the project, it wouldn't start at all. All the lights come on when I turn the key but no turnover or response from starter at all. I thought perhaps I may have accidentally knocked loose the electrical harness for some wired connection to that affect. After checking and confirming all connections I still get nothing in terms of turnover and starting but when the key is left in on position, there is a rapid ticking, like a timer, coming from what seems to be the fluid pan.

Car is salvaged in 2004 in flood. I kept my car! Things are now failing. I'm a single, disabled senior without family and friends to help me. Plus, I am new to nevada since March 2014. I really need "help" with my vehicle or I'll be without transportation, thanks