Lawrence Nguyen

Recently on a couple hundred mile drive the codes P0700, and P0740 have appeared. Before hand (about a week before) the code P1457 had appeared. I somewhat understand what to do about the P1457 and I know the P0700 is a result of P0740, but can the P0740 be a result of the P1457?

Also I am wondering for any solutions for this. The car is a 2001 Accord lx. Thanks!

Tonyrome216

just take the car to pepboys or autozone so they can read the codes for you and its free

Lawrence Nguyen

Thanks, I did just that and they said it is a transmission problem. Taking it to a transmission mechanic tomorrow, I'm hoping it's not an expensive fix...

jdmcertified909

just hope its a shift solenoid

P0740 HONDA - Transmission Lock-Up Control System Fault

Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted

When is the code detected?
Diagnostic trouble code P0740 is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.

Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission shift shock
- Vehicle may not shift into the highest gea

P0740 HONDA Description
The torque converter clutch solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.

Lock-up operation, however, is prohibited when A/T fluid temperature is too low.

When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

and the P1457 is not transmission related. its a evap leak

s2ki.com/stor/library/TSB/a03-001.pdf <<<<< copy and past in browser

P1457 won't make the car run bad at all. It just means the EVAP canister & the related system of hoses & valves isn't airtight like it should be.

Check this stuff in this order. As soon as you find something that doesn't behave like it should, fix or replace it. Then hope it was the only thing wrong with the system...

Some background for the electrical troubleshooting:
All the solenoid valves have constant +12v supply from the main relay. When the ECM wants to energize a valve, it closes the ground side of it's circuit. If the +12v supply is broken, then the ECM can't energize the valve. If the wire to the ECM is shorted to ground, then the valve is energized even when the ECM doesn't want it to be.

EVAP Purge Control valve - between intake manifold & valve cover.
Valve should be normally closed, so it will hold vacuum when it's not energized. Ground is supplied by pin A6 of the ECM to open the valve. So jumper pin A6 to ground, turn on the ignition, and check again - this time it should NOT hold vacuum.
EVAP 2-way valve - underneath the car roughly under the left-rear seat. It's a little can with 3 hose barbs & a solenoid valve attached to it. Leave the connection on top, disconnect both on the side, attach MityVac to lower one. Normally closed, it should hold vacuum when the solenoid is not energized. When the solenoid valve is energized, it should not hold vacuum.

************ THANKS to rjpjnk for the following clarification about this valve.
The 2 way valve is complicated. It should hold vacuum on the lower port when the solenoid is *not* energized. The solenoid when energized provides a passageway to bypass the normal path between the upper port and the lower port. That's why it is called a "bypass solenoid" btw.

The upper port of this wretched valve from pluto is actually designed to open to pass vacuum or pressure to the lower port when the vacuum or pressure exceeds a certain threshold (a kind of hysteresis effect). The slight resistance to flow is what allows a certain design pressure to remain in the fuel tank. Once this is exceeded, the excess pressure (fuel vapor) bleeds over to the canister side. At any time, the ECM can force this to happen by activating the bypass solenoid. It does exactly this during the p1456/p1457 diagnostic tests. The upper side port is always connected to the top port (the third leg of this beast) which is connected directly to the FTP (fuel tank pressure sensor). Did you know the FTP sensor is not in the fuel tank? ;-)
************

EVAP Canister Vent Shut valve - attached to the charcoal canister underneath the car.
Normaly open - when ECM closes pin A4 to ground, it should hold vacuum.

EVAP Charcoal Canister - the big can under the car, about under the left-rear seat.
Leak test: Connect all the hoses together, plug the Vent Shut valve, connect the MityVac. Pump vacuum while watching the fuel tank pressure (FTP) sensor. You can read FTP sensor voltage with a scan tool, or use a voltmeter between pins A29 & C18 at the ECM. Pump down to 1.5v & it should hold that vacuum for at least 20 seconds.

EVAP 2-way valve vacuum & pressure test.
If you get this far you'll want the manual for a good picture of how to connect the hoses. Keep pumping the vacuum pump & it should stabilize between 6 & 16 mm Hg of vacuum. Then pump pressure, it should stabilize at 8 mm Hg or more of pressure.

Then there's a test of the ORVR Vent Shut valve, which is located on top of the gas tank. You check vacuum & pressure at a couple hoses alongside the fuel filler pipe. If the valve is bad you drop the gas tank to replace it...

PhatAccord92

iTrader: (1)

P0700 codes are transmission dtc's.
P1456 is an evap code. they are not related.
P0740 is torque convertor clutch failure. how is the transmission condition? is it jerking or slipping? more than likely the transmission and or torque convertor is going bad. notorious on 98-02 accords, especially the v6 models.
as for the P1456, check your gas cap. was the gas cap loose? is the seal on the gas cap worn/cracking? if so, they will cause dtc's

jdmcertified909

did you not read what i posted? you posted the same thing over again but with less detail and i dont see where you got a p1456 all i see is 57 which would be the bypass valve evap system. a p1456 is a gas cap ill give you that. but i think you read wrong.

PhatAccord92

iTrader: (1)

touche. you have corrected me again. my apologies. having a brain fart that night

Lawrence Nguyen

Thanks for all the replies! Anyway I took the car into a transmission mechanic (I don't know anything about cars other than basic maintenance) and he says it's a large problem with the transmission and a 2500 - 3500 fix... However after we took the car to him all three of the lights went away and have not come back on since then (it's been about a week). I still notice some problems with the transmission in D4 so I'm not really sure what to do, I'm getting the transmission fluid changed today to see if that helps any. I'm about to go to college and this is my first car so I don't have a lot of money so hopefully I can just drive around with just the transmission fluid changed.

BigMike2001

what ever turned out with that p0740 code?

fstassgsr

i just bought a 98 2 days ago and it has this problem. its shows the p0740 and the p1457codes. its having problems shifting from gear to gear sticking and slipping. i just checked the trans fluid level today and its way over full. im going to honda tom and buying some new fluid, so i can drain whats in there and put new in. im hoping this might fix the problem but if it doesnt does anyone have a diagram showing which solenoid is which and where they are located on the automatic trans so incase replacing the fluid doesnt work i will try replacing these solenoids. Also this is the first automatic trans i have owned do they have a drain plug just like the manual honda trans do. i know on some auto trans you have to take the pan off or whatever. dont really know anything about automatic transmissions.

fstassgsr

any suggestions

fstassgsr

i need a diagram showing which solenoid is which and where they are?

fstassgsr

i found diagram

fstassgsr

im going to the junk yard tom to see if i can find one. what all can i look for that would have the same trans. i know 98-02 are the same right but like would one out or a tl or something work. or even one off a 4cyl.

fstassgsr

alright so i replaced the tcc solenoid and the fluid and the light is still on and still no 3rd or 4th gear

HardyParty

I'm having this same exact issue. Code P0740. I just replaced the automatic tranmission, also I threw in a new torque converter.. trans has no problem going into gear, with that being said there is so slips or anything obvious as to my transmission being messed up.. doesn't effect the performance of the vehicle once so ever.. if anyone has any information I'd highly appreciate it. I'm clueless. I just don't want this thing to lock up on me.

nicolaselias

Are you sure you replaced the transmission with an identical model with the same numbr of solenoids to the one that came off?

HardyParty

yes I did. It has 4 sensors just like my old one. My car is 1999 Honda civic EX.. the replacement trans I got came out of a 2000 Honda civic DX.