Artbuc

My niece's TSX threw P0128 a while ago. We cleared it and her CEL has come back on and gone off by itself a couple times. We didn't bother getting the codes read. The CEL light just came back on again and the codes were P0128 again and P0456. Of course we don't know if P0456 is brand new or if it was the problem causing the CEL to come on and off.

In any event, can I assume these codes have nothing to do with each other? P0128 is a Cooling System Malfunction which I believe is most likely a weak thermostat. P0456 is a very small leak in the EVAP system which I hope is nothing more than a bad gas cap.

TexasHonda

My Acura TSX shop manual does not suggest any connection between two codes. There's a long diagnostic trail for this code. Suggest a shop manual to DiY. If you don't have one, check ebay seller automanualsource for a $21.99 download manual. That's what I have and it's very good.

good luck

Simba91102

Remember that the CEL is for emissions related malfunctions, and unless you absolutely need to pull out all stops to save the earth, you can take your time with the light (though it sure is annoying). Of course if there are drivability problems which present themselves along with the light, then there is most likely more than just a little extra CO or volatile spirits going on. And.... in Mass. for instance (I can't speak for other states), you won't pass the annual safety inspection if the CEL is on.

Artbuc

The only posible connection would be if P0456 is a spurious code being thrown because the ECM is confused. I have had that happen with my Toyota and Lexus cars. You may get a code for a particular problem and, if you let that code persist, other totally unrelated codes appear which go away when you fix the first problem.