So i have had the check engine light on with 2 trouble codes (1411 and 1423). I was driving with those codes for about half year till i decide to fix it. After i replace all vacuum hoses and line the check engine light was still there so i decide to check my car again. This time i didn't have two previous codes but instead it has code p0741. I drove the car 3 days and on 3rd day light went off for 4 hours and than came back on. After another 4 days light went off again this time it was off for 3 days at end of 3rd day it came back on with code p0741. Some of my friends recommended to use LUCAS FUEL TREATMENT on two full fuel tanks and that should help me clean my system , if that don't help they recommended to change trans fluid ,they say it cant be anything serious since light is going off and on ,please share your thoughts about this problem thank you.
P.S
day before i replace my hoses and vacuum lines there was only those two codes 1423 1411 , so 0741 must occur right after i fix first two.

 

What do those codes mean?

 

P1423 and P1411 is for secondary air system There was a lot of problems with vacuum hoses going to combi valves on the back of both heads. i fix it

 

When you see a code you need to first figure out what it means -
the first two were secondary air pump codes. Changing the vacuum hoses was the right thing to do. If they return you'll need to make sure the air pump is working...

As for the last code - It is something different. Before you listen to a bunch of people with uninformed ideas it would be better for you find out what problem the p0741 code is telling you about.

Just so you know P0741 means the following

17125/P0741/001857 - Torque Converter Clutch: Stuck OFF / No Power being transferred
Possible Causes
Automatic Transmission Fluid (ATF) Level not OK
Transmission Sealing faulty
Automatic Transmission Fluid (ATF) dirty
Torque Converter faulty or incorrect Torque Converter installed
Solenoid Valve 7 (N94)/Pressure Regulating Valve 4 (N218) faulty
Torque Converter Pressure Valve faulty
Valve for Torque Converter Clutch faulty
Torque Converter Lock-Up Clutch faulty/worn

Possible Solutions
Check Automatic Transmission Fluid (ATF) Level
Check Transmission Sealing
Check Automatic Transmission Fluid (ATF)
Check Torque Converter
Check Solenoid Valve 7 (N94)/Pressure Regulating Valve 4 (N218)
Check Torque Converter Pressure Valve
Check Valve for Torque Converter Clutch
Check Torque Converter Lock-Up Clutch


It's not rocket science - Go ahead and dump fuel treatment in if you want but it would be like working on a finger when your knee hurts!

 

THANK you NH USA for your respond !Thing that bother me the most, why check engine light it's always on, and every other day going off ? ,so you think by replacing trans fluid, it should help ?

 

You said the light was on for six months before you decided to fix the secondary air pump problem. Maybe you need to fix things when the light first comes on so it goes out for awhile...

As for the new code -- I can only tell you what it means and what the possible fixes are. The rest is up to you..

PS it would be helpful if you told people which A6 you have you know year motor etc.

 

sry my bad its 2000 A6 2.7T with 120k miles ,btw check engine light went off today again sry i should explain myself better i mean light for 0741 going off and on like now its 3rd time in past 10 days ,light for 1423 and 1411 was always on !

 

The light is telling you that something is wrong. It usually dosen't go off all by itself. I suspect low trans fluid but don't know