Hello, everyone! I am looking at buying a 2003 Monte Carlo with P0742 and P0401 DTCs. The car has 160000 miles on it, so it is high mileage. I think the P0401 is due to carbon buildup on the EGR tube, but I haven't tested this theory yet. Any other things that might be causing this or easy ways to test anything? The P0742 I'm not sure about since the vehicle is high mileage. Does anybody know what I should check out to try to figure out what is throwing this?

 

These may give you a place to start and more information on your codes --->P0742 Torque Converter Clutch Circuit Stuck On OBDII Engine Light Trouble Code | Engine-Codes.com
--->P0401 Chevrolet Exhaust Gas Recirculation Flow Insufficient OBDII Engine Light Trouble Code | Engine-Codes.com

 

Thanks for your reply! I have looked up what the codes are, but I'm more wondering if anybody else has had either of these things. I'm more worried about the P0742 since it might require a new tranny if there's something seriously wrong, but it could be something as simple as a transmission flush...

 

The P0742 is most likely the TCC solenoid stuck on. It can be tested with a GM tech 2 scanner for amperage, current/voltage and on-off, otherwise testing requires removal of the side cover to access and test the solenoid. I just bought an '03 SS with 168,000 miles on it which also has tranny problems. Unfortunately, previous owners never did a tranny service and it will need to be replaced since 3rd gear clutch plates are worn out. Smell the fluid, if it has a foul, burnt smell and is black in color be cautious, there may be other problems just around the corner. If the tranny is original it probably doesn't have much life left.