tropicalpalmtre

i have a 1999 honda accord and the car keeps going into limp mode after a while of driving and wont go past 4000rpm, the eml is on and the codes are:

P1259 vtec system malfunction (this usually disappears for a week or so then comes back after erasing the codes)

p0420 catalyst efficiency below threshold

P0401 EGR flow insufficent detected

it goes ok once the codes are erased, but goes back into limp mode after an hour of driving and its doing my head in, ive noticed not long before it goes into limp mode between 2500-3500 the acceleration goes really sluggish, almost like its pulling the car back if you know what i mean, then will continue on up the revs (not sure if this is related but worth mentioning). any ideas of how this can be fixed, really getting me down as i cant afford costly repairs at the moment, any help greatly appreciated

holmesnmanny

Take off the vtec solenoid and clean out the gunk.

MAD_MIKE

P1259 is the VTEC oil pressure switch.
Verify the crankcase is full of oil.
Visually check that the switch is not leaking oil.
Disconnect wire harness from pressure switch.
If not leaking check for continuity across the switch terminals.
Turn Ignition to ON.
Verify the terminal of the wire harness has battery voltage to ground, check the Blue/Black wire to ground, there should be battery voltage.
Verify their is battery voltage across the two terminals of the wire harness.
Turn ignition OFF
Remove the single wire connector from the VTEC solenoid.
Check for 14-30Ω to ground.
Verify the VTEC pressure switch is not gummed up.
Verify the VTEC solenoid filter is not clogged up. (check the Accord FAQ at the top of the page).

P0401 EGR port is most likely clogged. This will cause the stumbling, you are feeling the lean misfire created by the clogged EGR port.
Depending on engine there are differnt ways in cleaning the port.
F23/J30 require the upper intake plenum to be removed to clear the port.
Gaskets are about ~$15.

Ignore P0420 until all other codes have been cleared.

I prefer to fix the problem and clear the PCM of codes by pulling the memory fuse and going for a ~30mile drive to see if any codes come back or are pending. Pending codes do not always cause the CEL lamp to illuminate, if there is a code pending repost back here.

tropicalpalmtre

thank you both for your replies, can you tell me where i can locate the vtec oil pressure switch and solenoid? not to mechanically minded any information a great help

MAD_MIKE

Open the hood, look at the distributor, directly behind it will be a green round plug going into a sensor, that is the VTEC oil pressure switch #12. The aluminum block that sensor is screwed into will have a metal cylinder mounted to the top of it, attached via three bolts. That is the VTEC solenoid, #9

tropicalpalmtre

thanks mate

swet tea n bluz

Mike could you post the location on a 01 3.0 ?

swet tea n bluz

i found this:

https://www.hondapartsnow.com/Page_P...umbers=&PNC=11

#13. would this be the cause of my p1259? i also have a code p0132

MAD_MIKE

Topside of oil filter mount. #14 is the VTEC solenoid, #17 is the VTEC oil switch. #16 is the oil pressure switch(idiot light). I use Majestic Honda when trying to locate/reference a part.

swet tea n bluz

so i should replace #14 and #17 to fix my code? i did check my oil level and its up to spec and no dent in the pan. pull the batt to clear codes?

MAD_MIKE

I'm blind, I didn't see post #8

If you are getting a VTEC oil pressure switch code, use post #3 as diagnostics. Being a V6 there may be different values for the resistance.

P0132 is for O2S B1S1. High voltage is usually indicative of running rich. You may want to back probe the sensor with a volt meter or use a scanner to monitor voltage output to verify if it is running rich.
Clear the code and see if it comes back. Verify the connection and wiring harness are fine and undamaged.

swet tea n bluz

will do.

eksine

I just cleaned the egr ports on 2 cars. take off the electrical connections and hoses so you can take off that big upper intake manifold. the gasket is metal, you can reuse it. use metal tools or manicure tootpicks. here's the kicker: use a vacuum on it while you clean, that main hole with the black carbon buildup that you're trying to clean out, well it goes to the watter passage, use the vacuum otherwise you simply are clogging the water passge. since you are taking off the intake manifold do yourself a favor and clean out that...I think its the iac control, it has a electric motor and spins what looks like a dremel cutting bit insiode of it, pretty sure its iac valve aic valve or something. it is the electronic thing on the bottom of the intake mani, buy lots of brak cleaner, like 10 cans or more. clean out the maze under and on top of the manifold gasket, they are air circuits for the intake manifold. check youtubes, theres tons of info there