Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

Another owner experienced EPS – Power Steering failure with error code #22 so he decided to send in the controller to me.



His issue seemed to be not permanent because he can at least recover the EPS by resetting the controller and he won’t see the issue until he stops and restart the engine.

The next time he starts the engine, he almost always get the EPS warning light so he had to reset the controller again (after reading the error code, of course).



For this failure mode, the battery voltage is also very important so please make sure to check the battery condition as well as the connection at the battery posts.

After some email exchanges, he had his EPS controller removed and confirmed that it was indeed the famous 023 version.

You can check this by looking at the part No. located at the side of the controller box.

There is an issue with the current rating of the internal relays and Honda upgraded it to high current capacity one for the later model.



For UK NSX, if it is around 95 – 97 models, you may have this 023 version EPS on your NSX.

Sooner or later, you will experience error code #22 issue with this 023 version EPS controller.

By now, everyone knows that there is a nice logo on the A/C CCU as well as on the EPS controller.


There is two relays to be replaced.

Honda upgraded just one of them but I prefer replacing both of them.

The relay removed from the board on the left and the high current capacity spec on the right.

Noticed the different number of pins at the terminal??

You need to install this new higher spec relay into here and it is quite obvious that you need to drill additional holes to the board.

Very delicate process so just take your time.

As the extra holes won’t be the ‘through hole’ type as seen on the original board, you must create better bonding by stripping off the coating and creating extra patch.

Ran out of the time for the day so will continue tomorrow.

Kaz