ajparry89

I have a 2004 aveo with about 186k, and the MIL is on, and once you start to drive it, the light begins blink, however the engine does not seem to be running extra rough. the codes are P0300 engine misfire, and also P0404 EGR Feedback signal (probably needs a valve), P0455 large EVAP leak, and P0700 for transmission malfunction. additional code in the trans computer is P1781 Engine Torque Signal. So i realize that the codes are indicating misfire, and i will say that at times it does misfire. but it blinks all the time even when its running fine. im sure it needs a tune up, could probably use an EGR vavle (i know that can cause running issues too), but the OTHER problem is that it does not shift into 4th gear. I am not sure if that is related to trans codes that are present or not. Will the engine light blink because of this trans code? or will it not shift into 4th gear if the engine light is blinking? just trying to get an idea as to what MAJOR issues might be present, before i through money at it trying to fix a misfire when it needs a transmission or something like that. if anybody has any ideas, let me know, thanks!

oilcanhenry

I have found that on the smaller Chevy motors, like your Sonic, when you get the dreaded OBD II code 0300, it tends to be a bad coil pack or if intermittent it's going bad.

ajparry89

Ok. but nobody is familiar with the trans not shifting into 4th gear? sound like a major overhaul problem? havent done much work on these trannys before, not familiar with them and what it requires to repair them. thanks all!

Carlodi4

It could be in limp mode from all the codes. I had an O2 code and a cam sensor code. And the car didn't want to go over 50mph.
what RPMs does it shift into the other gears at.
*I'm assuming you drive an automatic

tech2

an 04 aveo is a Korean Daewoo vehicle with a chevy badge. these engines had problems with valves sticking. put a vacuum gauge on a port connected to the intake manifold. view the needle on a test drive when the problem is occurring. a rapidly dropping out needle indicates a valve problem. valve replacement would be required or a new/used cylinder head. the cost to fix it is more than the cost of the vehicle.

other issues i have seen are torn air intake snorkels. the rubber snorkel breaks on the bottom from repeated bending when the air filter is checked. This can let false air into the engine and lean out the fuel mixture. it could potentially cause a lean misfire. this fix is easy and cheap.

good luck