CraigWeber Posted September 7, 2014 Share Posted September 7, 2014 1998 Legacy Outback with new rebuilt engine recently installed. I drove it for about 9 months with no trouble codes. Recently, the check engine light goes on while driving at 40mph on freeway. The trouble code is p0740 - Torque Converter Clutch Circuit Open. The check engine light will go out at low rpm's - ie city driving at 25mph. It only goes on when I accelerate on the freeway. The transmission shifts perfectly both in city driving and on the freeway. The rpm at 65mph stays about 3000. I found a used speed sensor that I may install, if necessary, but not sure if it has anything to do with the trouble code - P0740. The tranny is not overheating, the AT indicator light has never gone on. I did notice when the light first went on that my tranny fluid was low - about 2 quarts. I inspected the tranny, hoses, radiator coolant, and found no evidence of leakage anywhere. This is a very perplexing problem which has caused me to limit my long distance driving. Does anyone have suggestions on my problem? Are there other diagnosis procedures that I should consider? Thank in advance for your help. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted September 7, 2014 Share Posted September 7, 2014 is the trans mission oil pan dented? Quote Link to comment Share on other sites More sharing options...
CraigWeber Posted September 7, 2014 Author Share Posted September 7, 2014 Thank you for your response. No dents in the tranny pan. I did read another thread which indicated that a dent could cause trouble code P0740. I don't think that this is the cause of my problem. Would you happen to know if the speed sensor, located next to the differential dip stick could cause this trouble code? Thanks Craig Quote Link to comment Share on other sites More sharing options...
ocei77 Posted September 8, 2014 Share Posted September 8, 2014 Do a search for Subaru DTC. There are at least 5 things they suggest you check. First is the circuitry of the Duty B solenoid.. I have had this issue when I lost my tach. in a 98GT. When the circuit there drops and I show 0 revs, the switch doesn't know what the actual engine speed is and sent that code. I pulled my harness, cleaned the contacts and since then no codes. If you can't find the list, pm me your e mail and I'll send it. The one I have is 294 pages O. Quote Link to comment Share on other sites More sharing options...
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