I recently switched ECU's and now my check engine light is throwing code 90. I looked up the code and found that it means "Evaporative Emission Control System Leak Detected". Is this something I should be worried about?

I was running a modified chip for a while, and had my intake and catback upgraded while I was still running the modified chip. Now that I have switched back to my stock OBD-II chip (i have a 99 gs-r) I am getting this code 90. Perhaps the chip is complaining about the upgraded intake or catback that it didn't have when I was running this stock chip before? Any ideas on this?

Thanks!

 

 

I actually am having the same problem. I recently did the auto to manual conversion and swapped my ECU out. Getting the same code, but experiencing no side effects.

 

Here this explain a little more in detail about Code 90.

This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

This really holds true for me because I can smell gas vapors near the fuel filter and charcoal canister.

 

So is this going to be a cheap fix? I'm going to try resetting my ECU and see if it throws the same code again.

 

Well mine was a very obvious fix. When my auto to manual was done, the sensor for the canister was not plugged in. All I did was plug in the sensor and reset the ECU. You definitely should try resetting the ECU first, however if the code 90 comes back, check your hoses all around the fuel filter/charcoal canister area and the most obvious making sure your gas cap is tight. I dont know why you changing out your ECU would make a difference. Goodluck.

 

Yeah me either. I think the modified ECU i was running was running too rich though, thats the reason I put my stock ECU back in. I don't know if this could cause the error 90... Anyway, whats the best way to reset the ECU? Just unplug it? Or can I just unplug the battery.

 

Take the negative off the battery and let it sit for 3 minutes.