FAQ : Top Ten Reasons Why VTEC Doesnt Work

FAQ : Top Ten Reasons Why VTEC Doesnt Work


Honda variable valvetrain technology known as VTEC is known for it’s ability to maximize power in a small displacement engine. Whether you are talking the VTEC in your stock Honda or Acura, or whether you have swapped Honda engines, VTEC is a feature that most Honda fans look for when shopping for swap motors. When your VTEC doesnt work, it can be extremely frustrating and difficult to track down the issue.

It’s not always smooth sailing however, because when you own an older Honda or Acura or swapped a VTEC engine into a car that didn’t originally have VTEC you can run into issues. One of the most common questions we receive here at Pro Street is “Why doesnt my VTEC work?” or “My VTEC doesnt engage, what’s wrong?”


Today we’ll be counting down the Top Ten Reasons Why VTEC Doesnt Work or might not be engaging, ranking them by how common these errors are.

Why VTEC doesnt work

10. Check Engine Light



Otherwise known as the Malfunction Indicator Lamp (MIL) the check engine light or service engine soon light is a clear indicator that something is wrong. Any number of OBDII related errors can cause your VTEC to not work, or not engage.

If you have a check engine light or service light on make sure that the error is not related to your engine or sensor inputs. It’s one of the leading causes or problems when VTEC doesnt work.

9. VSS


If your Honda ECU loses the Vehicle Speed Sensor (VSS) reference, it will not be able to engage VTEC because it will not know the car is moving. If you have completed an engine swap and have a mismatched vehicle speed sensor, either replace the vehicle speed sensor to match your ECU, or install a Dakota Digital Translator.

Some of the best vehicle speed sensors for your Honda are found below :

8. Oil Pressure

A lack of oil pressure, enough oil or similarly related lubrication issues can cause problems with your VTEC system. Without the proper oil pressure the VTEC pressure switch will not tell the ECU that it’s safe to pressurize the VTEC oil system which will push the VTEC locking pins in place.

Without a proper pressure reference, your big VTEC cam lobe will never get going. Without the right level of oil pressure, VTEC doesnt work.

7. VTEC O-RING / Spool Filter


We’ve seen this one quite a few times, especially from customers with high mileage Honda engines. The spool filter is what Honda calls it, it can also be called the VTEC Solenoid gasket. If clogged or dirty this can also cause problems with VTEC engagement. Replace this filter immediately to resolve your issue. The part number for this spool filter can vary depending on your engine, but this part is easy enough to replace.


7. Tachometer or ICM


One of the more obvious problems that can complicate your engine swap or VTEC troubleshooting. Whether you have a problem with your ICM or distributor, or there’s a problem with your internal ignitor if your Honda ECU loses the ICM or Engine Speed (RPM) signal, there’s no way for it to reference when to engage. Resolve your tach issues to get your VTEC mojo back on the road.

6. Temperature / ECT Sensors

Your Honda Engine Coolant Temperature sensor is important to the operation of your VTEC system. Many people actually mix up the ECT sensor for the oil pressure sensor as the plugs can be similar depending on what Honda engine you are swapping into your car.

5. VTEC Pressure Switch Malfunction


VTECAt the halfway point of our Top Ten Reasons Why VTEC Doesnt Work Guide and it’s our first VTEC component failure problem. The VTEC pressure switch is responsible for informing the ECU that there’s sufficient oil pressure to engage the big VTEC lobe.

Check the function of the VTEC pressure switch by testing for continuity between the VTEC pressure switch and the Honda ECU in question. Shown is a B16A VTEC solenoid valve and pressure switch.

For the specific ECU and generation of your motor, search our site or check out the Honda Swap Guide here and part 2 here. Use the right ECU to ensure that VTEC kicks in, and fix your issue when VTEC doesnt work.

This example shown to the left is on a OBDI P28 chipped ECU, the pins in question on the P28 ECU harness are D6 for the VTEC Pressure Switch, and A4 for the VTEC Solenoid Valve.

Make sure to check out our How To Wire VTEC Guide for further details. It’s one of the leading causes when your VTEC doesnt work.

This part can fail due to contamination, failure or damage and without it you won’t be hitting VTEC any time soon. Need a How To service your VTEC Pressure switch?

Check out our handy guide on how to resolve any VTEC pressure switch issues by giving you a step by step troubleshooting process.

4. VTEC Solenoid Valve


Not to be confused with the Toyota VSV, the VTEC Solenoid Valve is part of your Honda VTEC system and is the unit that engages the locking pins and actuates the big cam lobe. A problem with this unit will mean that mechanically engage the pins that kick the big lobe on your VTEC camshaft into gear. Checking continuity to this unit in our example of a OBDI Civic with a B16 will be Pin A4 on the OBDI P28 ECU.

3. Oil Problems


Many problems can attribute to your oil being the main culprit to your VTEC problems. We’ve gone over the obvious oil pressure issues, but that’s not where the list of causes stop. Dented oil pans, cracked oil pickup tubes, insufficient oil, old or contaminated oil or thinned out oil can all cause your VTEC to fail.

 2. Throttle Position Signal


Problems with your Throttle Position Sensor or throttle body will most certainly cause issues with your VTEC. Although the main problem can usually be found in the form of a P0123 OBDII code, if you have a OBDI Civic, like our current example it won’t be so obvious.


Learn how to test your Honda Civic Throttle Position Sensor (TPS) in our How To guide located here. We have another writeup in case you need to test the continuity back to your ECU from the throttle position signal wire or resolve the P1121 OBDII Check engine code.

1. Wiring

The leading issue behind the VTEC not working of course is the wiring. When you think about the number of Honda Swaps that happen every year, and then consider how many of those jobs were done by a friend or a relative it’s easy to see where the problems can arise.

Incorrect VTEC wiring or the wrong wires being run into the cabin when you are installing a VTEC motor in a non VTEC car, are just a handful of problems that can stop VTEC. Frayed wires, damaged wires or wires exposed to the elements can arc out or short causing further issues.

Enjoy our VTEC troubleshooting Guide? Have any questions for us? Leave them below and let us know!


  1. I am looking to swap a b16a motor with a hydro tranny out of a 1992 honda civic into a 1990 honda civic si hatch. I would like to know if there is some literature on what is needed to make this swap happen and done properly.

    • Hi Carter, thanks for commenting.

      No problem, we have this writeup in our archives and I can have it posted for you.

      What you are looking for is a cable to hydro conversion, and there’s quite a few ways you can approach it. I’ll post the link here when we bring the page back.

      Thanks for reading.

      • First I must say thank you for a quick response. But what i am really looking for is all the info to swap this motor and tranny over. I really appreciate all info from you. What I need is more like a Hanes manuel on this motor swap because I am better with info than just pictures or hands on.

  2. My honda civic b16a vtec was on the dyno today for a tune cause i had the motor taken out an put back in but now theres a ruff idle and the vtec is not engaging.the tuner said i must check the distributor cap.pls can some1 help me.

    • Hi Mo, thanks for reading.

      Couple of questions.. did you change anything when putting the motor in? Are you sure you don’t have the MAP sensor and TPS sensor swapped?

      Also have you measured your VTEC Solenoid switch?

  3. Hi I have a b18c Integra type r I just change the clutch and now when I turn the car on it idles at low rpms but when it get warm it goes to 1500 rpm and my Vtec is not kickin in…if some one can help me out…

    • Hi Henry, couple of quick questions.

      1. what year is your integra?
      2. do you have a datalogger or scan tool
      3. Does the car drive normally once warmed up?

      Let us know and we can help narrow down the problem

      • I have a 1996 civic hatchback with a 1998 integra type r motor and yes the car drives normally but stays at 1500 rpms once warm and the Vtec is not kickin in…n I don’t know what a data logger or a scan tool is….

  4. I got a b20 with a gsr head and blow my motor and I fixed but now the check engine light its there and my vtec its not working and also a change the oil pan and I put a moroso oil pan I dont know if thats the problem and I put a skunk2 ultra street manifold can some one help me ?

    • Hi Juam, thanks for reading!

      okay, so you’ve got a CR-VTEC setup.. I assume your VTEC worked before?

      The moroso oil pan isn’t going to affect anything unless you don’t have enough oil in it and it’s causing a lack of pressure., have you pulled your code yet?

      • Yea the vtec worked before i fixed my engine, i tryed using a computer to check why i have a check engine light but im not sure how to check it with the computer like as a civic, crv or integra to get the codes

  5. im 26 yr old single mom, work on cars, not expert. struggling finacially- found deal on used 1998 honda accord ex coupe. original engine 2.4L 6cyl. 3.0L 6 cyl VTEC honda engine.(was told is 2006,not certain).200,000 m on trans. dont know miles on engine. P4257- O2 sensor-not replaced yet. valve cover gasket made w high temp gasket maker, new spark plugs– {P1399,P0300-misfire detected}, P0301-P0302,P0303,P0304,P0305,P0306–pistons one through six misfires detected. couple bad wires need replace- but why all six detecting misfires??? current engine compatible w car??? reprogram computer to engine specs since not factory bc disconnections durring repairs??? other parts, sensors, modifications to make the car and engine work together as best possible that anyone can tell me would be awesome???

    • Hi Nicole! wow sorry to hear about the car but glad you came here.

      Okay couple of quick questions..

      which engine is in your 98? its the 3.0 liter J30 I’m assuming? what harness are you running? Did the car ever run right or has it always been like this?

  6. hi peeps my revs only go to 4and half on my vtec 1.6 sport civic 04 and its like limiter kicks in weird, but when cold will go round rev range with vtec trying to kick in at 4 an a bit thou revs. needs a o2 sensor and management light on could this be interfearing with my vtec and poss oil change and vetec solanoid clean up as well? any ideas please thank you.

    • Hey Brendan, thanks for reading.

      Okay.. quick question here :

      1. does the car run normally up to 4.5 rpm?
      2. what modifications do you have done to the car?
      3. Does it feel like fuel cut or spark cut?
      4. When did this start happening?

      Let us know and we can try to help! Thanks for commenting!

  7. I have a Honda Stream RSZ (R18A Engine) and the VTEC isnt engaging. There is no CEL and the O-Ring, Oil Pressure and Pressure switch all checked out to be ok. The Mileage is still pretty low (38k). Interestingly, a few weeks ago I reset the ECU and the car drove perfectly, with vtec engaging, for around 2 days before going back to the non-responsive state… Any ideas?

    • Sounds like a strange issue to be sure Roger… Let’s start with the basics.

      Can you test to see if your VTEC solenoid is actually opening? Any stored DTC codes / even deleted or cleared ones? Do you have a scan tool that you can read Live Data from your Civic (USDM) engine? This shouldn’t be happening to you at such low mileage, but I’m sure its something small.

      Let us know and we can try to help you out. Thanks for commenting

  8. Good write up thanks.iv recently bought a 1992 crx del sol b16a.when its fully warmed up it wont vtec..it reachs vtec and starts missing badly..is tho ecu holding back or a bad spark issue??when its below full temperature it will fully rev out but vtec isn’t engaging.

    • Hi Christy, couple of questions

      Have you tried swapping your VTEC solenoids? and when you say it’s missing badly do you mean spark is missing? What ECU are you using?

  9. Hi,

    i have honda civic 94 swapped engine with D15b. Since the day of swapping im facing an issue of fluctuating RPM from 1000-1500 continuously even the engine temperature is hot. Can anyone help me out since there is no one here to figure out the exact problem.

  10. Hi, I just swaped a b16b into eg6. the problem is that my Car does not have a dashboard so i cant get the vtec enagaging, i got on tachometer but I´m not sure how to get the signal into the ecu wich is oa OBDIIB. also the speed sensor is installed, but do i need dashboard in order to get the vtec working? thanks.

    • Hi Diego! Thanks for commenting!

      Okay! you swapped in a B16B and need to connect VTEC. What ECU are you running and did your EG have VTEC stock? You don’t need the tach to get VTEC to kick in, so let us know what your setup is and we can help. Thanks!

  11. My name is Aldo. I have a 1998 civic dx hatchback that i just installed a obd1 b18c engine into. I used a rywire engine harness with rywire chasse harness, and im using an obd1 p72 ecu. The harness is supposed to be plug and play for my chasse, but im still having the issues that i was trying to avoid. Speedometer doesnt work and vtec does not engage. I did everything rywire guys told me to do and more to resolve issue. I checked all wiring and related plugs for continuity(vtec selinoid, vss), checked related sensors and replaced some(oil pressure switch, vss). I checked vss continuity from plug in engine bay, through ecu, to plug behind guage cluster and its all good(cluster good aswell). Checked vss ground and electrical current and its all good. Thought it might be ecu so I plugged in another and im still having same issues so my obd1 p72 ecu is fine. Engine worked fine in previous car (95 acura integra ls) using same ecu. I did not take apart, open up, rebuilt, etc, engine in the transition of the swap. I pulled engine from one car and put into the other. Please! Any ideas? Thank you.

    • Hi Aldo, wow okay sounds like a complex issue.. couple of questions :

      1. do you have the stored trouble code?
      2. Have you tested the sensors? MAP / TPS / VSS?
      3. Have you measured the signal at the ECU harness?

      Please let us know and we can try to fix your VTEC issue.

  12. Bought a car 1996 honda civic ex took it a mech to have work on it and he told me VTEC wasn’t kicking in 3-5th gear took forever trying to get over 60 . car has a d16y8 5speed manual swap in it with correct ECU and the obd2 sensor won’t even read when plugged in turns on read error restarts process . check engine light is on not sure what to do

    • Hi Mario, thanks for reading!

      If your VTEC isn’t working you should start with taking the time to read your OBDII code using a data scan tool. When you said OBD2 sensor, did you mean the scan tool? Using this you can see what sensor is causing a problem with your VTEC. Anything from your MAP sensor, TPS sensor or oil pressure sensor can cause your VTEC to not engage.

      If your scan tool isn’t working for your VTEC Civic, check what ECU you have. Do you know which one you are using?

      • The scan tool doesn’t work when plugging in it turns on and says error try again …. It’s a d16y8 manual 5 speed motor with a 37820-p2p-a32 ECU in it …. I’ve asked around as was told it’s right ECU

        • Hrm.. Have you tried to test your OBDII port? you may be missing power or ground which could cause an error when reading the code. Alternately have you tried to jumper your ECU harness? the two pin blue harness by your ECU?

  13. I’m having problems with my CRV..HONDA 2005 jumping and bucking …We bought a V..t…switch ..let a friend put in on but after a day it started back ..I don’t know if he even bought it and put it on …cause I heard things about him after …I’m checking on it now to see if he bought it ..so I guess that’s the problem of jumping ..any thing you can help me with I thank you ..Ab..

    • Hi Abbie, thanks for reading!

      okay, so couple of questions for you :

      1. Is your CRV check engine light on?
      2. does VTEC engage?
      3. Is there a RPM range where this issue happens? Is it consistent or only sometimes?

      Please let us know and we’ll try to help! Thanks for commenting!

  14. I need some help …. I’ve change the dizzy yesterday on my b20vtec and now vtec dont work, it was working fine before broke down with the old dizzy

    • Hi Mauricio, thanks for reading!

      Couple of quick questions, did you change anything else? What year make and model of VTEC engine do you own? Do you have any check engine lights? Changing the distributor should not stop VTEC from kicking in

  15. 2002 honda accord…just spent $3500 on a rebuild transmission…drove it less than 30 miles and had to have it towed back..same problem I was having before the transmission swap..( not engaging into 3rd gear..hesitation from 2nd into 1st gear..)
    I basically could drive over 25 mph….check engine light on and D light blinking)
    So when they get it back, run the new code it ends up being my v tech solenoid…my question is..
    Would a v tech solenoid that’s faulty, cause my car not to shift properly???
    The original codes when they first got it was 780 and 730..I guess points to internal transmission..
    I’m really pissed and beside myself that I spent $3500 on a trans when all I needed was a v tech solenoid!!

  16. 2002 honda accord…just spent $3500 on a rebuild transmission…drove it less than 30 miles and had to have it towed back..same problem I was having before the transmission swap..( not engaging into 3rd gear..hesitation from 2nd into 1st gear..)
    I basically couldnt drive over 25 mph….check engine light on and D light blinking)
    So when they get it back, run the new code it ends up being my v tech solenoid…my question is..
    Would a v tech solenoid that’s faulty, cause my car not to shift properly???
    The original codes when they first got it was 780 and 730..I guess points to internal transmission..
    I’m really pissed and beside myself that I spent $3500 on a trans when all I needed was a v tech solenoid!!
    I’m not sure if I should take to small claims either..just trying to gather enough info


    • Hi Luke, thanks for reading.

      First off I would replace your 02 sensors, as it’s most likely your front oxygen sensor that needs replacing. From there the only thing left is to check your VTEC actuator. First track down which 02 sensor is the problem and replace.

      Thanks for commenting, let us know how it turns out

  18. I have a 99 civic EX with a USDM B16a, valve springs, retainers, Skunk 2 LMA’s, pistons and rods, ITR Cams, but my vtec isn’t engaging. Have tried everything, oil pressure is good, solenoid is clicking when the wire is touched with a power source (12v battery), on the rocker assembly is fine, vtec locking pins and everything is there, there’s RPM signal, no check engine lights, good voltage to everything, even tried another solenoid that I know for sure works. Every tried directly wiring the important things, wired vtec straight to the ecu it’s tuned on (A4), wired the knock sensor straight to the ecu as well. While driving we ran a wire from a power source straight to the solenoid to try and engage vtec manually while giving it gas and nothing, my tuner has tried to move vtec as well to a different engagement point and nothing. I’m pretty stumped considering all the things that are needed for vtec are there but it is still not engaging, any input would be helpful, thanks.

    • Hey Omar, thanks for reading and commenting on our VTEC guide. It always sucks to have these kinds of issues, so let me get that out the way first. After that you’ve covered quite a bit when it comes to your engine. Can I ask a few more questions?

      1. Did your VTEC ever work? or is this a new engine swap?
      2. Original ECU?
      3. What does oil pressure look like?
      4. If your VTEC solenoid is clicking over, do you see the camshaft rocker pin move at all?

      Let me know and hopefully I can help. Thanks for commenting and reading!

  19. Hey I have a jdm b16a ob2a with stock ecu in an ek. It seems like vtec is engaging at 5800 but right after it engages it seems to disengage? There is no cel and the oil is topped up.


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