P0421 Smart Auto Trouble Code

P0421 Smart the main thing to check is to verify the operation of the VCT solenoid. You're looking for a sticking or stuck VCt solenoid valve caused by contamination. Refer to vehicle specific repair manual to perform component tests for the VCT unit.

Remove the air filter box assembly so you can access the transmission range switch. Turn the key to the ON position, but do not start the vehicle. Move the shifter to the neutral position. Align the alignment holes between the switch and the shift lever. Insert a 5mm drill bit into the adjustment hole to verify the proper alignment for the neutral position.

P0421 Smart Possible Solution:

Brake Switch Out of Self-Test Range Indicates that during Key On Engine Off (KOEO) Self-Test, BPP signal was high. Or during Key On Engine Running (KOER) Self -Test, the BPP signal did not cycle high and low. Open or short in (BPP) circuit Open or short in stoplamp circuits Damaged PCM Malfunction in module(s) connected to BPP circuit (Rear Electronic Module [REM] Windstar and LS6/LS8 and Lighting Control Module (LCM) Continental and Town Car) Damaged Brake Switch Misadjusted Brake Switch Check for proper function of stoplamps. Follow correct Self-Test procedures, refer to Section 2, Quick Test.

P0421 Smart Description For All Models :

P0421 Smart Trouble Repair :

The scent may P0421 Smart signal oil or coolant leaking from their normally closed-loop systems, or it may indicate dangerous exhaust gases invading your car's interior. Car and truck exhaust contains toxic gases such, so if the inside of your car as if you were standing behind your car, get out and get it fixed. Fight the urge to take a little nap first. So sleepy. That's the carbon monoxide talking, friends. At least open a window on your way to the shop.

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