CKF Bypass Trick

UPDATE 10/07/09
A poster by the name of William pointed something wrong with the CKF bypass trick information posted here, and well, it’s now time for yet another CKF revision! Not sure how or why my information on this was slightly off, but this article has been revamped and should have a lot less people wondering why this trick isn’t working for them (yet it does for others? weird). What William pointed out will not only fix the Code 9 issues some of you are experiencing, but is the right way in performing the CKF bypass altogether. Thank you William.

UPDATE 2/19/09 (now superceded)
I’ve slightly revamped this page to better explain the CKF bypass trick due to the CEL 9 issue that has recently arisen. There are now two methods you can perform – but –  I HIGHLY suggest performing method 1 first then move onto method 2 (noted in red)  if you get a CEL code 9 once you’ve tried method 1. If you’re not getting a CEL code 9 with method 1 there is no need to perform method 2 – otherwise you may give yourself CEL 54 or 9 if you apply method 2 when it is not required.

UPDATE 9/3/08
There have been reported CEL CODE 9 (CYP) issues once the CKF bypass trick has been performed on certain OBD2 civic/integra vehicles. There is a fix for this problem which is explained within the procedures in RED below.

NOTE: You DO NOT need to perform the new method if you’re NOT getting CEL code 9!

SYNOPSIS

This article describes how to trick a U.S. OBD2a/b (96-01) Civic & Integra ecu into thinking a CKF sensor is wired in when there actually is no CKF sensor available.

What is the CKF sensor?

The CKF is the Crank Fluctuation Sensor. All U.S. 96-01 (OBD2) Honda/Acura vehicles have this sensor which is integrated onto the oil pump. (CKF images soon)

This trick is aimed to help hybriders who are using a U.S. OBD2a/b ecu in their vehicle (for whatever reasons) to power their engine – yet their motor is lacking a CKF sensor.

Here’s a few scenarios where this bypass trick comes in reeeal handy:

  1. When using a JDM OBD2 B-series engine in a U.S. 96-01 civic/integra powered by a U.S. OBD2 ecu. JDM engines do not have a CKF sensor on the oil pump like US OBD2 engines do. Some people want to stay smog & street legit; this bypass trick allows this very desired feature without needing to convert to OBD1. It’s also been proven that you CAN pass Smog and the state REF (here in CA) while this mod is in place – passes the OBD2 scanner tool.
  2. When using a U.S. OBD2 B-series engine in a 92-95 Civic/Integra powered by a U.S. OBD2 ecu (via jumper harness adapter). Same info from above applies here.

For the unknowing – when using a U.S. OBD2 ecu & the CKF sensor is not wired in, the engine will run like total crap not to mention you’ll get a nasty CEL (code 54). This trick basically taps the CKF into the CKP and shares the signal. This bypass trick will save you time, money (around $300), and severe headaches!

OBD2a Civic/Integra

Please refer to the ecu pin out page for the CKF pin location(s): OBD2a pin out schematics

Get yourself 4 Scotch-lock/tap splicers
Sometimes dubbed ‘quick splice’, these can be real life savers. Get 2 of these bad boys and a pair of pliers for the squeeze-splicing portion of the job:

Locate pinout C1 (CKFP) and C4 (CYPP) ; using the pliers quick-splice these two wires together as shown.
Now, cut C1 (blue wire w/red stripe) AFTER the quick-splice. This will sever the connection that leads to the actual CKF sensor out in the engine bay. This will allow C1 to piggyback the C4 signal properly and without issue.

Locate pin outs C1 & C4 quick splice C1 & C4

Locate pin C11 (CKFM) and C14 (CYPM) and quick-splice these two wires together as shown.
Now, cut C11 (white wire w/red stripe) AFTER the quick-splice. Doing this will  sever the connection that leads to the actual CKF sensor out in the engine bay. This will allow C11 to piggyback the C14 signal properly and without issue.

Locate pin C11 & C14 Quick-splice C11 to C14

The reason behind cutting  C1 and C11 AFTER the quick-splice, is to prevent conflicts with the ECU that may arise such as  CEL code 9 (CYP) and P-code 1337 (CSF sensor no signal).

FINALLY, RESET THE ECU BY UNPLUGGING THE ECU PLUGS FROM THE ECU FOR ONE FULL MINUTE OR PULL THE ECU (ie.BACKUP FUSE) IN THE ENGINE BAY FUSE BOX FOR ONE FULL MINUTE TO CLEAR THE ECU’S MEMORY.

That’s it!
Your finished OBD2a quick-splice job should look something like this:
OBD2a CKF mod complete.

OBD2b Civic/Integra

Please refer to the ecu pin out page for the CKF pin location(s): OBD2b pin out schematics

Locate the blue ecu plug “C”:

Locate OBD2b blue colored "C" plug

Now locate pinout C22 (CKFP) and C29 (CYPP) ; using the pliers quick-splice these two wires together as shown.
Now, cut C22 (blue wire w/red stripe) AFTER the quick-splice. Doing this will sever the connection that leads to the actual CKF sensor out in the engine bay. This will allow C1 to piggyback the C4 signal properly and without issue.

Locate pin C22 & C29 quick-splice C22 & C29

Then locate pin C30 (CYPM) and C31 (CKFM); quick-splice these two wires together as shown.
Now, cut C31 (white wire w/red stripe) AFTER the quick-splice. Doing this will sever the connection that leads to the actual CKF sensor out in the engine bay. This will allow C31 to piggyback the C30 signal properly and without issue:

Now locate pin C30 & C31 Quick-splice C30 & C31

The reason behind cutting  C22 and C31 AFTER the quick-splice, is to prevent conflicts with the ECU that may arise such as  CEL code 9 (CYP) and P-code 1337 (CSF sensor no signal).

FINALLY, RESET THE ECU BY UNPLUGGING THE ECU PLUGS FROM THE ECU FOR ONE FULL MINUTE OR PULL THE ECU (ie.BACKUP FUSE) IN THE ENGINE BAY FUSE BOX FOR ONE FULL MINUTE TO CLEAR THE ECU’S MEMORY.

That’s it!
Your finished OBD2b quick-splice job should look something like this:
OBD2b CKF mod complete.

PROPS

Special thanks to Honda-Tech member omahaturbocivic for THIS THREAD who exploited this trick – and anyone else (unmentioned) who thinks they’ve contributed to this! Also thanks to William for bringing up the required cutting after the quicksplice!

126 thoughts on “CKF Bypass Trick

  1. trick did not work gave my 98 tegy spark thou but would not run a lil back fire blew a battery out trying wat else could i do swaped a 93 block to my 98 need help ps timings perfect n on top dead center

  2. hey i swapped a 96 gsr into my ek hatch and i used this wiring method. I plugged in the Obd2a GSR ecu and no CEL comes on but the car bogs. When im running a chipped obd1 GSR ecu it runs fine, what could the problem be?

  3. I just got a 96-99 JDM ZC Sohc motor. I put it in a 1996 honda civic ex. I did the wire trick and t’s still running like shit. The Vtec oil pressure and soleniod connectors are unplugged and the knock sensor was broken due to the wiring harness. Do I need to jump to OBD1 ecu to fix my issuses? I’m planning on swapping the y8 head back on to the motor once i purchase a honda pulley holder.

  4. i got a fresh b18b1 on my 98 ex coupe i’m and using a 98 dx harness and i got ckf problem if i use the trick u say will i be able to ref my engine with no problem

  5. Kincaid- first off, what ECU are you using? the 96 EX ecu? or a JDM SOHC ZC ecu? Of course if you don’t have the VTEC components wired up or the knock sensor the ECU will be in LIMP mode and run like ass. After you performed the CKF trick, are you still getting the CKF CEL code?

  6. 96GSR- could be a number of things that could be causing your ‘bog’. The best way to pinpoint the problem is by checking the CEL code you may have then go from there.

  7. Yogi- technically yes, you could but its a much cleaner and hidden job when performed at the ECU plugs vs. out in the engine bay, especially if you plan to BAR your car. And yes converting to OBD1 is a big perk in getting around this annoying sensor!

  8. i have a 96 ex civic that i swapped a jdm d15b vtec, i am useing my stock intake and wire harness. but i am throwing a p0335 (crankshaft position sensor) would this trick work for me? if not any ideas thanks !!!!!!

  9. Hey katman, I dropped a d16z6 in my 96 civic dx. I am using the same wire harness obd2a, I did both methods, but both methods seem to be the same. Before I did this trick, I had a ckf code number 9, when I did this trick, I got a ckp code 4. The car is idling at 1500 rpm and also won’t let me rev pass 3500. I am using a p28 ecu with a obd2a to obd1 conversion harness with hondata s300. I also switched out the guts from my distrubutor, switched the d16y7 guts into the d16z6 caseing so the distrubutor would line up. My distrubutor plug is one plug instead of a 2 plug that d16z6 have. Please help katman!!

  10. how will this affect things if in the future i want to run hondata and tune?
    also from what i am understanding, i need to try method 1 first and IF i get CEL 9 then i try method 2?
    thanks for the awesome write up!

  11. Rick- there’s actually only 1 method now since my most recent update. This mod shouldn’t affect anything regarding a Hondata, in fact, an S100-300 won’t even look for the CKF sensor so you don’t even have to perform the CKF mod being that you’ll have to convert to OBD1 anyways.

  12. civic ek – because you converted to OBD1, you didn’t have to perform this trick at all. I would undo the CKF mod and see what happens. If you still have problems I think the source of your problems may lie with your distributor parts swapping. Perhaps you swapped something incorrectly or crossed a wire wrong.

  13. matt96ek- YES you should perform this CKF trick if you are using a US OBD2 EX ecu to power the D15B engine. If you convert to OBD1, you don’t need to perform this mod.

  14. malcolm- Yo. The reason for cutting C4 & C14 is so the piggyback riding these 2 wires are doing don’t mix signals resulting in CEL 9. I’ve recently updated the article on April 28th. If you’re still having CKF bypass problems, look over the article again and see if it resolves your CKF issues.

  15. 610player- if you are still having CKF bypass issues, please re-read the article as I’ve updated it as of April 28th. No idea why your battery blew out. Perhaps you didn’t perform the CKF bypass trick correctly.

  16. Katman

    im guessing it will still be ok even if i have the OBD2a to OBD1 adapter? its pretty much plug and play?

  17. Rick- good question actually. I have not tried running an OBD1 conversion harness while the CKF mod is in place. Try it, see what happens, let me know!

  18. well since the hondata ecu is OBD1 and doesn’t look for the CKF signal, im just gonna go ahead and see if i can just plug the ECU harness straight into the OBD2 to OBD1 adapter and see if it works. if not, then i’ll try the bypass trick.

    thanks and i’ll keep you updated

  19. I have an Acura TL 2.5 with the crank case position sensor code. The car will crank but wont start. What wires can i jumper for this model and do you have a wire diagram and location for me to work off of?

  20. MAN,
     6 YEARS LATER. I JUST BOUGHTA JDM B20B. VERIFYING I HAVE NON-VTEC B20Z2 USDM BLOCK CRACKED REPLACING WITHJDM B20B  USING OBD1 ECU STOCKALL THROUGH. DO I NEED TO SWAP OIL PUMPS OR I'M ALL GOOD 

  21. I did this on my 98 crv,  I will throw a cylinder 1 misfire code every few weeks. Car runs great no obvious misfire that I've determined spark plugs look clean too. Other than that I have no issues! I seriously appreciate your help! 

  22. You only need to swap the Z2 pump over if you’re going to use an OBD2 USDM ecu. If an OBD1 ecu is being used, no need to transfer the OBD2 oil pump w/sensor.

  23. I’m sorry, I have no experience with the TL engines and their sensors or wiring. The CKF trick I have posted here is strictly for the civic/integra platforms.

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