2005 Chevy Trailbrazer. Check engine light and check gauge lights have come on. Now there is a ticking noise coming from under the at idle and while driving!

SOURCE: 2005 chevy cobalt check engine light

You need to get the computer scanned. This can be done at Auto Zone or similar parts stores free of charge. More than likely you will just need new spark plugs and/or plug wires but I cannot be certain without the engine code.
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SOURCE: 2003 Silverado rough idle, idles good after "check engine" light

Check your o2 sensor voltage, those trucks are real bad for o2 sensors, and yes if one sensor is reading 0mv, the others will start to drop out, and the vehicle will run very, rough. You also may check fuel system pressure, should be almost 60p.s.i. If its alot lower, Id be looking into a fuel pump. If that vehicle is drive-by-wire (no throttle cable), the throttle bodies get very dirty and cause that concern also. Id start by having the vehicle scantested.

SOURCE: 2005 chevy equinox temp gauge showing hot fan

check the coolant temp sensor

SOURCE: hold light blinking, check engine light on, engine slows down

check tps sensor (throttle position sensor in backside of the throttle cable) and map sensor (manifold absolute pressure on front little 1 inch sensor with vacuum line) make sure there plugged in. the ecm (engine control module driver side inner fender) and tcm (transmission control module under dash) both need the data to know when to upshift and increase fuel/air. Otherwise the computer runs default values and guesses off of other sensors giving poor performance. also disconnect battery for 15 min. usually resets aveo service lights if you dont have a scanner.

SOURCE: Rough idle

I had the same exact problem on my 2004 Colorado (3.5L). Cleaned the MAF sensor (with MAF sensor cleaner) and throttle body/plate - cleared it right up.