Hello! I’m posting this in the Accord forum because I’ve had no luck in the Odyssey forums, as this is a one-year-only model for first generation Odyssey, and therefore a limited audience there. And since she’s basically an overgrown Accord, I was hoping you all could help. I know this is long, it’s been long for me too.

She’s a ‘98 Odyssey F23A and I’ve been fighting a VTEC code since day one. I’ve read every forum post I could find, found a lot of repetitive information and none have solved it. It has myself and several other professionals stumped. Here’s the story.

I purchased it in July of 2015, had VTEC code at time of purchase. She had a blown head gasket when I bought her, so I had cylinder head checked while I had it off. Assembled and road tested, code would return each time after about 20 minutes of driving from cold. Once the code would set, you could clear it and it would reset as soon as VTEC was requested. Let her cool down to dead cold, you could start all over.

I replaced the VTEC valve and pressure switch with a Honda part. The screens on the original were completely clean. Tested everything I could test using Alldata. Could not test oil pressure at the VTEC valve since I didn’t have the adapter. Oil pressure for the engine was good. Figured this was above my paygrade (I have 19 years VW experience, this is my first Honda), so I enlisted the help of a Honda guru I knew. Granted, he had retired prior to VTEC, but he’s no dummy.

After a lot of reading on both our parts, he felt it was mechanical, I felt it was electrical. First he rebuilt the ECM, no luck. Since my first guess was wrong, he went looking for oil pressure loss and ended up finding a plug on the end of a cam cap was loose allowing oil pressure to drop near VTEC valve. Tightened plug and problem went away until October of 2016, lasted about 20,000 miles.

This time it’s a little different. This time, code returns as soon as you accelerate and VTEC is requested. Can do it from dead cold. Vehicle must be under load, will not do it on the lift or in neutral. Immediately I checked the plug on the cam cap and found threads stripped and cap finger loose. Retapped and installed new plug, cleared code and performed ECM reset. Code came back immediately. Figured, OK, I’ll play with it later...Continued to drive it to work and back, code cleared itself after a couple weeks...stayed out for about two months, came back this January. Took a stab and tried using an engine flush hoping maybe there was something in the VTEC system that was blocked and this would clear it. Engine ran much smoother than before, but had even less power - Spoke with my buddy again and we figured she was just worn out.

Purchased and installed a JDM engine on 3.4.17 - swapped entire intake from old motor to avoid any conflicts with current ECM, Swapped the (new from 2015) VTEC valve, new Honda knock sensor. Cleared codes, reset ECM, road tested. Very strong pull until 1-2 shift, then transmission slipped out of gear, slammed back into gear. MIL came back on for VTEC code, vehicle then slipped out of gear on anything other than a very light acceleration. Transmission does not seem to know when to shift either.

OK, the transmission has always been a little iffy, but before I made another $400.00 guess, I took it to another guy at a shop who has tons of Honda experience both dealership and aftermarket. I asked him to make sure it really needed a trans and didn’t just lose programming or something and to diagnose the VTEC issue. His diagnosis: “Yes, it needs a transmission, and it needs a VTEC valve”. He said the ECM is working properly and everything is getting proper signal. We both agreed that I’ve ruled out anything mechanical by replacing the engine.

So I went and got a JDM transmission from the same guy I got the engine from and installed it today (3.18.17). Transmission issues solved.

I was skeptical about his diagnosis on the VTEC valve since I had replaced it with a factory part. So, first I removed the VTEC valve and took it apart, made sure the plunger moved freely, no scars or burs. I cleaned the whole thing, cleaned inside the switch, the accuator, everything. Assembled, installed and road tested. Code came back the first time VTEC was requested.

Next, I unplugged the VTEC oil pressure switch and jumped the terminals at the connector to trick the computer and bypass the VTEC oil pressure switch. Code came back the first time VTEC was requested.

Then, I swapped the solenoid with the one from the other engine. Code came back the first time VTEC was requested.

So, I think I’ve disproved his diagnosis that the VTEC valve has failed. It’s obviously not mechanical at this point. RIght? So that leaves wiring harness and ECM? But they apparently test good.

What am I missing? Any help is greatly appreciated!

Cheers!

Mike

 

Check the oil level on your car and see if it is low, i fou d out on my car that it was an oil leak on the back of the engine, i change the valve cover gasket and the problem looks to be fixed from code p1259, try replacing the gasket and remember to use the appropiate torque and patern for your car,, let me know if it fixed the problem

 

Thanks for the reply! I guess I should have come back and labeled this "Solved". Oil level was good, as I had just replaced the engine and replaced all the fluids. Turned out to be an VTEC oil pressure circuit issue. Got some help on the Odyssey website, which might end up helping someone else too, so I'll just leave this here if anyone is interested:

Ongoing P1259 VTEC Code

Cheers!

 

You are going to need to get a hold of the adapter and test pressure going through the vtec pressure switch. You can also check to make sure that the rocker arm assembly is moving freely. Also check to make sure there are no dents whatsoever in the oil pan that could be causing the oil pickup to not get sufficient pressure.

 

Hi, I'm new to the forums and have done a lot of reading up on this issue but can't seem to "solve" it. But I have a P1259 code I've been struggling with for awhile. I have an '01 Civic EX 1.7L (all stock) with 192k miles. Just to make aware, I did a head gasket/water pump/timing belt replacement awhile back and car ran good but at certain RPM the car would hop (around VTEC rpm, almost like I hit the rev limit early - about 3k) so I took the VVT sol off and found crap in the filter screen. Replaced the screen and that solved the "hopping" issue but doesn't fix the P1259 code. Checked oil levels, changed oil, Changed the VVT sol (tested to make sure sol we're working and both work), changed oil pressure switch, checked wiring from ECU to each the VVT sol and the pressure switch and wires are good to the computer. Changed the connectors on both the sol and the pressure switch just cause I noticed a crack in one of them. Nothing seemed to "fix" it so I'm having a hard time believing it's electrical but not ruling anything out at this point. I tested the oil pressure by removing the oil pressure switch on the VVT sol housing and piped in a 100psi gauge. rev'd the car to 3k RPMS (don't read any oil pressure until I and jumped the VVT sol to the pos off the battery to activate it) but only at 3k RPM I only had about 25-30psi. Did the test again only at 4K RPM and hit the limp mode rev limit and only had about 40psi. Reconnected all connectors and removed the gauge and was able to rev the car to 5K RPM before hitting a rev limit. Was told I should have 60psi at 3k RPM with no load on the car (reving engine sitting in park) but I'm not even close to that. Is there anywhere else besides the oil pressure switch I can read the oil pressure? if I check it at the oil filter housing, what kind of pressure should I see? Also I noticed my rear cam seal is leaking...could I be losing enough pressure there to cause the code? I drove the car like this for a week to work and back and it runs GREAT, but the CEL light won't go away and I can't get it inspected till I take care of this headache. Any help is much appreciated. Thanks in advance!