A Toyota C1201 trouble code can be very difficult to diagnose and fix because it’s such a general trouble code.
However to make it easy to find out the exact issue, then you need to use OBD2 scanner to find out the error codes.
C1201 TOYOTA Common Reason for this fault
- Large Evaporation system leak
- Loose/faulty Gas cap
Description of C1201 Code
If a fault is found in for example Toyota Truck‘s engine control system and is detected through the Control Area Network (CAN), the fail-safe feature bans the operations of VSC and TRAC. When the signals from the engine are input normally, the fail-safe is cancelled and the DTC is not stored.
How to Troubleshoot Toyota C1201 Code?
Three Codes are related to each other to clear the C1201 Code.
P0455: Evaporator Emission Control System Leak Detected (no purge flow or large leak)
P0441: Evaporator Emission Control System Incorrect Purge Flow
C1201: Engine Control System Malfunction
The two P0 codes suggest an emission leak in the system. Technically it may be in the filler collar, or the line to the charcoal canister, but for the most part it’s just a leaky gas cap. Either a cap wrongly mounted or one worn out.
The C1201 code is the one which tells the vehicle to turn on the light of the check engine and to disable the traction and VSC. Basically, when the other two codes pop up, this one is responsible for letting you know that there is a problem there. This one can also be solved by changing the other codes because they are the ones that caused it.
How to Fix C1201 Code?
A new gas cap is definitely not going to fix your problem. You’ll have to find out what yours means and fix the problem.
There is a false perception that newly gas cap would clear the vehicle into turning the check engine light off. It’s not – unless it was the problem in the first place.
It’s a step of process you have to go through to fix a code by applying a simple solution before going for an expensive one if it not fixed.
Tighten the gas cap and clear the codes, (They came back approximately 4-5 restarts later).
If the cap was leaking, then Clean and grease the gas cap’s seal and clear the codes.
The result was the same as Solution #1
If above method didn’t work then purchase OEM aftermarket gas cap, don’t try to put low quality cap, it will not fix the problem.
Sometimes the new seal cap wouldn’t fix the issue, after a few days the light came back with same issues then what you have to do.
Find the original cap from aftermarket and make sure it has an original seal cap swapped the new seal onto the original cap and voila! Problem solved
After any of these fixes, you’ll need to clear the codes from the computer. You can either use your code reader to do this the easy way, or disconnect your battery for 10 minutes or so.
If All These Method Wouldn’t Work Against Toyota C1201 Code Problems and Troubleshoot
Then, look at the rest of the method. This is where things could get costly. Perhaps it is safer to take it to a shop that can check it for leaks. The fuel filler collar, the charcoal canister and the VSV valve will be areas of concern.
According to Toyota Support Center About this particular problem