12.12 Too High Idle Speed (Have to Perform Self-study again after ECU is
Power off)
Yes Remove the failure
displayed
1 Put the ignition switch to “ON”. Use a failure
diagnostic tester to check if any failure
information record exists.
No Next step
Yes Adjust or replace 2 Check if throttle valve plate is locked and if
failure exists in electronic throttle body.
No Next step
Yes Repair or replace 3 Check if the canister control valve, the fuel
pressure regulator, the positive crankcase
ventilation vacuum pipe and the vacuum pipe of
brake system are mounted steadily or they are
damaged.
No Next step
Yes Next step 4 Run the engine at idle speed and use neutral. Step
on the accelerator and observe if the idle speed is
too high.
No 6
Yes Repair or replace
the vacuum booster
5 Clamp the vacuum pipe and observe if the idle
speed becomes normal.
No Next step
Yes Replace PVC valve
6 Replace PVC valve and clamp the positive
crankcase ventilation vacuum pipe. Observe if the
idle speed becomes normal.
No Next step
Yes Replace the canister
control valve
7 Clamp the canister control valve pipe and observe
if the idle speed becomes normal.
No Next step
Yes Repair or replace 8 Check if electronic throttle body is dumb or
locked.
No Next step
Yes Repair or replace 9 Check other parts of air intake pipe for leakage.
No Next step
Yes Next step 10 Check if the gasket of fuel injector is in good
condition.
No Replace the gasket
Yes Replace ECU 11 Check air intake system for air leak and air flow
meter for normal working.
No Replace the sensor
Note: Check if the system goes through self-study, if not, the system will be under
failure mode or an uncertain state all the time, which may result in too high idle speed
of engine. The other cause is air leak in the system, if air leakage in the system is too
large and exceeds regulation and control range of ECU, idle speed fluctuation may
occur.
