jnlzr

So i decided to tackle on the oh so common problem we may encounter... the head gasket.. i did everything correctly. car running fine, start up right away, and no more leaking coolant.... the problem is when vtec kicks in. the oil pressure switch should turn off... but it doenst and it throws a code after a while. (P2646)

i put in 0w.20 mobil one oil. and removed the vtec filter to clean it... no clog btw. is there something else i am missing? could i have assemble the cam and rocker arm and such incorrectly?

the car runs great up til 4k then it hits a software rev limiter...

all parts are from honda

Thanks All

Jimmy

2004 Civic ex

BlueEM2

iTrader: (1)

Generally when you post the car has thrown a code it REALLY helps to put what the code means so we don't have to search it up. Now I have to navigate away from the thread to look up the code.. So ... One sec!

Try using a 5W20 or 5W30 oil like recommended from the manufacturer and see if your results change... ill have to do some more searching here. Make sure your oil level is where it should be and reset the ECM

Clean the VTEC solenoid and make sure it's not faulty.

justprice2

According to AutoZone P2646 is:

VTECH oil pressure switch circuite low voltage
Probable cause:
Check engine oil level and pressure
Open or short circuit condition
Failed VTECH pressure switch


I got this code before, and the mechanic cleaned the solenoid screen, and cleared the code. He said if it came back on, it was likely the pressure switch. Well it's back on... so I'm thinking it's the switch...

Anyone know where it is on a 2005 Civic HX?

jnlzr

ok i'll try it tonight and see if there is any difference.. thanks for the help

lazlong

Most of the time when this happens the connector wasn't fully connected or a wire was pinched.

The VTEC oil pressure switch is right next to the VTEC solenoid. It comes off the same assembly.

jnlzr

so i went thru 2 oil changes ( 5w-20) and the vtec filter was replace. still the same problem... the solenoid clicks when i put 12 volts in it. but the oil pressure switch still stays on... i gonna order the switch from honda tomo and see what happen! thanks for the help so far!!!

BlueEM2

iTrader: (1)

Have you done anything with the switch?

jnlzr

i got instruction to see if the switch is working or not. so i unplugged the connector and use a dvom to see it i lose continuity when the vtec is active... no changes

Vtec off = Vps on
Vtec on = Vps off

my result was the Vps was on all the time..

lazlong

+1.

With the switch connector dis-connected are you getting continuity (ohms) at 3000rpm? no continuity @ 3000rpm- replace the switch

lazlong

Well, there you have it. You beat me to it.

jnlzr

so i replaced the vtec oil pressure switch and i am still getting the same problem.... could it be the solenoid itself?