Help with code 43 and 55

[mikey435]

Good morning all took my 90 out last night car was running fine then service light came on and she wasn?t running right went home checked codes and found code 43 and 55. Any advice on where to start with these codes?

[Will69camaro]

Had the same recently with mine with code 43 only. Did it by chance happen after driving and it being at operating temp a while and shutting off and restarting? Mine has done it a few times and it?s gone away. FSM points to it being a knock sensor. I just picked up a new one but have yet to install it.

If you don?t have a FSM I can snap a pic of the code 55 as well to help.

[Karl]

The knock sensor is on the driver side and is mounted "dry" into the block so it can be removed and no coolant will come out.

I had a code 43 years ago and my knock sensor was not mounted tightly as it would spin without a socket. I would start there.

[Will69camaro]

https://cimg2.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x300/94e93be9_7d8a_43dd_a558_1416ac08a2f7_1__024b1b079e bb880207efd02721d7705653d75645.jpg

[Karl]

Yep that's it.

[Will69camaro]

One thing I will say from quick search so verify it, is that code 55 is a O2 lean condition. I?d have some concern that if it?s running lean the knock sensor code may be related to it as well.

[mikey435]

I thought code 55 was a voltage code not a lean code

[mikey435]

I?ll check out that knock sensor when I get home thanks

[Will69camaro]

I thought code 55 was a voltage code not a lean code

This is what I see in my 1992 FSM.

[mikey435]

This is what I see in my 1992 FSM.

Thank you I?ll check my fsm this weekend and let you guys know what I find

[mikey435]

Had the same recently with mine with code 43 only. Did it by chance happen after driving and it being at operating temp a while and shutting off and restarting? Mine has done it a few times and it?s gone away. FSM points to it being a knock sensor. I just picked up a new one but have yet to install it.

If you don?t have a FSM I can snap a pic of the code 55 as well to help.

Yes it did it after being hot shut down for a bit and then restarted I?ll definitely check knock sensor

[Will69camaro]

Yes it did it after being hot shut down for a bit and then restarted I?ll definitely check knock sensor

That?s what mine has been doing for the knock sensor code. It says in the manual it runs a test and if it fails it sets the light. I got a sensor, just gotta get under it and see if it?s the connector, loose, or just replace it.