Code 25 and 26 and 51

[pilotkidmk3]

Hey guys I've been randomly getting these codes:25,26,51 from my check engine light. I know that 25 is the air fuel being to lean and that 26 is the air fuel being to rich does anybody know how to fix that? 51 is air conditioning OR neutral start switch and wondering if it might be showing up since the A/C doesn't work. I've tried reseting the EFI fuse and it goes away but randomly comes back. If you know anything about this I will greatly appreciate your help, thanks!:1zhelp:

 

[jetjock]

25 and 26 are usually caused by the engine not being in fuel control or a faulty O2 sensor. Check what the sensor is doing per the TSRM by using either the OX or Vf terminals.

The only way to get 51 from the AC is if it's on (AC button illuminated) or the AC amplifier is bad. Missing or broken refrigeration components are irrelevant.

That said 51 is usually related to the TPS. There are several ways to check it. One method is to use Vf at the same time you're checking the O2 sensor. That way you won't have to mess with the TPS connector. Again, see the book for details.

51 will not go away by pulling the fuse because it doesn't get set in memory. It's there until whatever is causing it becomes inactive.

 

[3p141592654]

If you are getting 25 and 26 together, and its a California spec car, then it can mean the engine rpm is varying too much between cylinder firings at idle. Its a very crude attempt at misfire detection that was added only to CA spec cars. Another cause of 25+26 is the ox sensor cycling too fast. I believe this was an attempt to catch jury-rigged ox sensors in place of the real O2 sensor.

Someone else had an intermittent 25+26 that was eventually traced to a BHG. Hope you have better luck.

 

[3p141592654]

I stand corrected, the other guy's problem was low compression in one cylinder due to a leaky valve.

http://www.supramania.com/forums/showthread.php?128359-Codes-25-and-26

 

[Nick M]

51 will not go away by pulling the fuse because it doesn't get set in memory. It's there until whatever is causing it becomes inactive.

When he had customers that monkey with cars (and you know that never happens), we adjusted it by having your buddy sit in the car and tell you the 51 stopped flashing.