Need Help - Check Engine Light

[Worm]

Hi I have just replaced the O2 sensors on my '94 auto and tried to reset the system but the check engine light still comes on. Did a code check again and it points towards code 42 and 41 meaning the O2 sensors.

Can someone provide some advice?

Regards Woon

 

[ftuhy]

Is it possible you mixed up connections for the front & rear sensors?

I.e., did you use OEM sensors with the proper length and type connectors, or did you splice in universal O2 sensors?

 

[EIFFEL]

Check the fuel pressure, It may be weak fuel pump.

 

[nsxtasy]

Codes 41 and 42 are for the oxygen sensor heaters, not the oxygen sensors themselves.

Recently I've gotten codes 1 and 2, the codes for the sensors themselves, even after replacing them. My next step is to take out the ECU and see if it needs refurbishing for leaking capacitors or broken connections. It may take a month or more before I know for sure.

 

[xory72]

I would check to make sure you did not mix up the connectors when reconnecting the new sensors. This happened to me when I did then over a year ago.

I had to confirm wire colors with the manual and sure enough ... I have them mixed up. Once I had then connected properly, reset the ECU and all has been good since.

Good luck!

 

[Jett]

I had my O2 sensors replaced twice before I figured out that it was the coil packs, even though I kept getting an O2 sensor code. When I replaced the coil packs (I did them all by myself!) the check engine light went away.

 

[Larry Bastanza]

tried to reset the system but the check engine light still comes on.

Regards Woon

Please explain what this means. How did you try to reset?

As mentioned above the 41/42 are hard heater filiment failures. Basically it is like a light bulb test, if the bulb fails the 41 and 42 will show up. Did you remove the 7.5 amp Clock fuse to reset the ECU? It will not reset after the fix on it's own, you need to remove the fuse to reset it.

Also you said "I" replaced the 02 sensors. Did you use generic sensors? Did you have to splice the wiring in for the new ones, or did a shop do this? Fill us in.

Regards,
LarryB

 

[NSXclear]

Codes 41 and 42 are for the oxygen sensor heaters, not the oxygen sensors themselves.

Recently I've gotten codes 1 and 2, the codes for the sensors themselves, even after replacing them. My next step is to take out the ECU and see if it needs refurbishing for leaking capacitors or broken connections. It may take a month or more before I know for sure.

Wouldn't it be easier to just switch it out with a ECU from a friend or someone that is willing to let you borrow a spare?

I would lend mine out to you, but I've had a lot of bad luck recently with lending out parts and tools to Prime members.

I would suspect a fuel pump problem if you changed them out and still getting code 1 and 2. Do a fuel pressure test to confirm.

 

[ftuhy]

Woon needs to answer the various questions (which CEL codes, OEM or spliced-in universal sensors, etc) posed in this thread. Otherwise, we're justing running in circles.

 

[nsxtasy]

Wouldn't it be easier to just switch it out with a ECU from a friend or someone that is willing to let you borrow a spare?

The code is coming up too infrequently for that to be practical. It lit twice in the past 3,000 miles since the oxygen sensors were replaced. So if I tried swapping and driving around for a couple of days, and it didn't light, I wouldn't have a lot of confidence that that's the cause.

Otherwise, if it were happening constantly or frequently, that would make sense as a way to diagnose it.

 

[docjohn]

ken you dipping your toes back in the deep end????:wink:

 

[Larry Bastanza]

Guys,

Make sure we do not mix up Woon's problem with Ken's. They are different, best I can tell.

Regards,
LarryB

 

[Worm]

Hi Guys

Thanks for the advices. Sorry for not responding earlier as have been tied up with other matters.

Firstly, the sensors that I bought are original Honda parts direct from Honda, Japan.

I cannot confidently say that the sensors are not wrongly connected. What I did was to remove the rear one first and fitted the sensor with the shorter cable as it was the same length as the one removed.

When I removed the front sensor, I realised that it was a Mercedes part with the Honda connector spliced on. The cable length matched the remaining new sensor so I am assuming that I have the correct sensor for the locations.

I will try some of the advises provided and hope to resolve the issue. In the meantime, any additional information will certainly help.

Once again, thanks to the NSX community for being so ready to help. It makes ownership of the NSX so much more pleasant and affordable.

Regards Woon