P1012 Toyota OBD2 may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments. As a result, oxygen sensors are likely to report fuel mixture problems.
The computer notices the canister is empty when it detects a leaner condition (all the vapors are used up) and it resumes normal fuel delivery. Some car manufacturers then close the vent solenoid but leave the purge solenoid open. That creates a vacuum throughout the entire fuel storage system. Once the correct vacuum is reached, it closed the purge solenoid and waits to see if the vacuum holds.
P1012 Toyota Possible Solution:
The firing order is an important part of the overall design of the engine and is determined during the design of the engine to eliminate as much engine vibration as possible. If the firing order is changed or adjusted, the ignition from the spark plug is delivered at the wrong time and the engine functions poorly or does not run. The firing order for a particular engine is typically found in the repair manual specific to that model.
P1012 Toyota Trouble Repair :
P1012 Toyota code shows that location the body harness connector, located in and around the left hand kick panel area or inside the IP (consult a shop manual for location). Water can leak into the connector from clogged sunroof drains, A-pillar leaks, or windshield or cowling leaks.