First post - code help needed

[LEMO]

CEL came on my 91. Had the code read, mechanic tells me that code "21 - O2 sensor" and code "51 - A/C idle..." were displayed. I checked the previous posts and saw were code "121" has something to do with the throttle and there is no combination which explains a reading of code "51".

Can anyone offer some help on what code "21" and "51" are?

Thanks

 

[CJF]

Pick up a Haynes manual on the way home from work. Shows the codes, and even how to check them yourself; all you need is a paper clip! (Not kidding.)

On the other hand, your mechanic's basically correct; 21 is deteriorating O2 sensor performance, 51 says the ECU's not getting a signal from one or more of a few switches. Did he say what he intended to do about it? Or did you just ask him to read them, in which case I certainly hope he charged you nothing or not much.

Stick around here and learn, and you'll be dealing with your mechanic a lot less.

Welcome,

Curtis

 

[LEMO]

Thanks. I figured the O2 sensor needed replacing. I'm gonna give that a try myself.

Thanks again.

 

[CJF]

Two of them; one before each cat. Replace both with OEM.

Cheers,

Curtis