James T. Samuel

Check engine light came on. Went to Auto Zone and these 2 codes popped up. P1259 & P1399. Can anyone point me in the right direction where to start? Car runs fine, no loss of power.

Chojun

Hi James, welcome to the forum! You've come to the right place.

P1399 is a temporary DTC - indicates a random misfire.
P1259 indicates a problem with VTEC - A problem in the VTEC Oil pressure switch circuit or VTEC solenoid valve circuit.

On the random misfire - see if autozone can clear any stored codes and drive around on it for a while, and see if any misfire code pops up again. If so, you may need to replace a coil pack or spark plug for the corresponding cylinder.

Regarding the VTEC DTC: First reset your PCM. To do this, with your car off, yank fuse 13 (7.5A) from the passenger fuse box - 10 seconds should do. Then replace the fuse and start your engine and get it up to temperature (radiator fan comes on at least once). VTEC kicks in at 4k RPM so you'll need to throw it into first gear and accelerate above 4K RPM in 1st for 2 seconds. If your check engine light doesn't come on, then try this test 2x more. Let us know if the light comes on and if so, what the DTC are (autozone). If it does, you'll need a multimeter to continue troubleshooting.

James T. Samuel

Thanks Chojun!! I will try this and let you know the results.

01tl4tl

is the oil clean? correct level? ever Seafoamed the oil before change- gets rid of passage clogs.
VTEC depends on oil pressure and pressure changes to operate

The Clock Fuse method resets the ECU- clearing all stored codes and forcing a full system self test, then go test drive!

I leave the clock fuse out for 1 minute- 10 seconds is probably fine, but a little extra to be sure never hurt~

01tl4tl

there is an idle relearn procedure you may need to do
its in our diy section

James T. Samuel

What is the Clock Fuse method?

Chojun

That's fuse 13 as I explained. Any luck?

Seabright

The clock fuse lets you cut power to the ECU without disconnecting the battery, which would cause the radio to power off lose the code. That leads to the maddening problem of the radio not taking the code when re-energized. Which will make you play with disconnecting the radio antenna or finding some deep in the earth parking garage where no radio waves can penetrate so the radio can take the code. Weird but true. Something about new radio transmissions like Onstar or satellite that started interfering with the radio security system. Aliens most likely.

Chojun

What?

Seabright

Here's one thread about it. Otherwise, you can just disconnect the battery to clear the codes but that powers off everything and you can be left with the radio problem. Aliens or gremlins.

https://acurazine.com/forums/problem...lution-609950/

Chojun

ah okay lol I thought we were getting into black helicopters and tinfoil hats stuff.

I'll bet people who have this problem have a fault in one of their grounds.

01tl4tl

some of our cars are just picky about taking the radio security code after batt disconnect.

So why even involve it when the CLOCK FUSE is THE SECRET BACKUP POWER TO THE ECU
removal of that fuse causes an ECU clearing, and reset of all codes, thats what you wanted in the first place!

James T. Samuel

So should I get someone to clear the codes, remove the fuse or disconnect battery to clear the codes?

Chojun

To troubleshoot your VTEC issue you need to reset the ECU. So yank that fuse for a minute.

thoiboi

it doesn't matter how to clear code, either way works

James T. Samuel

Okay but before taking the fuse out I should get all codes cleared and then troubleshoot?

thoiboi

taking out the fuse will clear the codes

James T. Samuel

Ok, to be clear. Taking out the fuse will clear the check engine light codes, check engine light will go off and then I can troubleshoot?

Chojun

Yup just do the procedure I described. If you lock it in first and gun it over 4K RPM for over 2 seconds and there's a problem with VTEC then the light will come on again. Get the codes and let us know what they are. If you do this a couple times and no light then you're good to go, just keep an eye on it.

James T. Samuel

Okay. I will do it this evening and report back.

James T. Samuel

Took the fuse out and ran the test. So far so good. No check engine light. Car is still running well. Didn't have to re-enter the radio either.

Chojun

Okay sounds like an intermittent problem, so you're probably good to go.

If it's been a while you may consider replacing your spark plugs - NGK Irridium IX - and maybe get your valves adjusted if you're over 110K and have never had them done before. As 01tl4tl says: it'll run like a 220hp sewing machine

01tl4tl

that clock fuse is THE WAY to clear codes- resets the ECU and readies it for road testing.

Im spending more time on a 2 wheel Honda now, 1500cc 100 hp, 110 ft lbs torque and 1100 pounds with rider...
one sweeeet 100hp sewing machine~

Can you say nearly 10 to 1 power to weight ratio!! Its frikken quick for its size
Bonus! looks very cop-like from both ends = no one wants to pass me, and most move out of the way~
Life is Good!
When riding with my buddy on a Harley, it looks like a cop is chasing him down the freeway