p1622 but not CEL

[donutholer]

On my 1999 z3 with a 2.5 m52tu, I scanned it from the hood while the car was running and it gave a p1622 code. However, I don't have a check engine light, and I know the light is working because during accessory mode, the check engine light is on. Is it perhaps a false code from the reader?

I'm only able to read codes with the engine running. Not sure if that's normal.

 

[ChrisD]

On my 1999 z3 with a 2.5 m52tu, I scanned it from the hood while the car was running and it gave a p1622 code. However, I don't have a check engine light, and I know the light is working because during accessory mode, the check engine light is on. Is it perhaps a false code from the reader?

I'm only able to read codes with the engine running. Not sure if that's normal.

A DTC can be present without CEL but not the other way round. An emissions fault generally needs to occur twice to illuminate the CEL but will be stored as pending without CEL Also, some codes will not illuminate the CEL at all as they have been determined to not affect emissions enough.

 

[donutholer]

A DTC can be present without CEL but not the other way round. An emissions fault generally needs to occur twice to illuminate the CEL but will be stored as pending without CEL Also, some codes will not illuminate the CEL at all as they have been determined to not affect emissions enough.

Ah so definitely a real problem and I should go ahead and replace the thermostat?

 

[ChrisD]

There are a number of things that might trigger this code - replacing the thermostat would be a good call.

 

[donutholer]

There are a number of things that might trigger this code - replacing the thermostat would be a good call.

what else can cause this?
bought the thermostat and I'm going be replacing it when I have the chance. Interestingly I drove the car for a while couple hours before seeing this code and to my knowledge it was running fine. I wont be driving it now, but It also did make a 20 minute drive to the garage after getting this code. Could I have already overheated my engine?

 

[ChrisD]

This code would not indicate that your engine has overheated. It is an emissions related code that tracks the warm up behaviour of the engine against a predetermined characteristic. It most typically sets when the engine does not warm up quickly enough. A faulty thermostat would be the most likely cause but there are many things that might also be in play - stuck in range sensor, cooling fan issues, engine running issues, wiring issues, and also, if this has only happened once, a false positive. If you already have the thermostat then it makes sense to change it - no harm in that.

 

[donutholer]

This code would not indicate that your engine has overheated. It is an emissions related code that tracks the warm up behaviour of the engine against a predetermined characteristic. It most typically sets when the engine does not warm up quickly enough. A faulty thermostat would be the most likely cause but there are many things that might also be in play - stuck in range sensor, cooling fan issues, engine running issues, wiring issues, and also, if this has only happened once, a false positive. If you already have the thermostat then it makes sense to change it - no harm in that.

I see. I didn't really have a good understanding of what the code was really saying. I do believe my temp gauge operates as normal, starts at the left and quickly gets to the middle and stays there. While under my car I noticed a lot of loose electrical connections in the front, as well as in the trunk. I didn't clear the code but I'll install it and clear that code.