x4and3r1991

hey everyone, wel i have a automatic 99 ex. and my CEL just came on, but its only when i am driving 60pmh-65pmh otherwise it wont come on, and when i turn the car off the light turns off too. so i checked the code and it was P0740 Torque Converter Clutch Circuit Malfunction. not really sure how i can be able to fix this. so any help would be great. or where i need to start from to fix this. thank you

ldyjam

My daughters car has the same issue. Sadly I see nobody had any advice. I'm waiting for the mechanic to tell us how much it will cost

EGgmannate81

Torque Coverter not engaging at highway speeds I believe. The few times Ive had this code it eventually required a new transmission to fix it. I am no mechanic but I see the stuff everyday and usually within a year or so the trans starts developing problems such as slipping and shifting hard. It is usually far too expensive of a risk to replace the torque converter as this normally doesnt fix the issue so just be prepared for that in case it does happen to you. Good Luck.

HardyParty

Hello, I'm having this same exact issue on my 99 EX... I just replaced the transmission over the weekend on top of throwing a new torque converter in it. Car runs fine, shifts smooth and I can get up to speed just fine. Nothing out of the ordinary for me to think something is wrong with my trans. Came out of a 2000 Civic Dx, if that helps at all. The car runs, it wants to go, and honestly the transmission feels strong. I'm about 100 miles out from the replacement and after 70 some miles I popped a check engine for this same exact code P0740. I just don't want it locking up on me or something. If someone has any suggestions or info related to my problem I'd greatly appreciate it. Thank you.

Ryanthegreat1

Very common issue on the 4 speed auto. The non serviceable filter slowly gets plugged with clutch material.

The first sign is the torque converter not locking up as there is not enough fluid flow to hold the 4th gear clutch and apply the torque converter clutch.

You could probably split the transmission open and replace the pickup filter but you are on borrowed time already. If you are going that far might as well replace all the clutch packs.

HardyParty

thanks for the info, I'm aiming towards one of solenoids being bad..I'm going to drain the ATF fluid and put Honda OEM type H fluid in an go from there.. really not trying to take off that transmission again and take it apart, if I would've known that I would of done it while the transmission was out... putting it in was too much fun lol

HondaToks

There is a Write up specifically on this. Using a EX (D16y8) Automatic transmission on a NON EX Civic (DX, LX, D16y7) will throw such code. And using a NON EX Automatic (D16y7 DX, LX) transmission on a EX Civic (D16y8) will do the same exact thing. Different gearing according to the write up.
Replacing a D16y8 EX Automatic transmission has to be replaced with a EX Automatic transmission.
Same goes for DX, LX model Civics 1996-2000