'98' Buick Regal

I have a 98 buick regal in which i have two codes showing up po171 and po742, I was told that the code po742 is the torque converter clutch circuit stuck on and if I get this change I might as well get a whole new transmission but I don't think a whole new transmission is needed. Can the torque be changed without dropping a whole new trans, and the code po171 I have no idea what that is, and also my check engine light just blinks on and off really fast. Can someone opinion my problem please.

Thanks mcn

Welcome to AF.

It would help to post your mileage and whether you have an LS or GS model.

When was the last transmission service? ATF and screen filter. The DTC P0742 does not mean the torque convertor is bad and warrants replacement. It could be electrical like a TCC-PWM solenoid and the valve body (hydraulic) area where it mounts.

DTC P0171 indicates the system is in a lean trim mode. Ideal fuel trim = zero. Greater than zero indicates the PCM is adding fuel to compensate for the lean condition. If fuel trim is less than zero the PCM is reducing the amount of fuel to compensate for a rich condition.

Here are the possibilities:

Check 02 sensor (Pre-CAT)
Check all vacuum hoses at intake system.
PCV Valve
Possible throttle body blockage (clean input screen and body)
IAC (idle air controller valve)
Check fuel injectors (bad o-ring seal)
MAF sensor
EGR valve

thanks for your reply, i have like 170,000 miles and my car is a LS. the 02 sensors, intake gasket, egr valve and pcv valve were all replaced. my last transmission service was at least 2 months ago and the oil was really black and i was told i did have medal in the screen.

The black transmission oil is not good but it is normal to get some metal shavings and clutch material depending on the mileage. Was the TCC DTC there before the tranny service and what type service was performed. Pan drop or a flush?