P21F5

Fuel Control System B Too Rich Off Idle Bank 1

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$17–89 (est.)

Symptoms

Increased fuel consumption
Black smoke from the exhaust pipe
Unstable engine operation
Power Loss
Smell of gasoline from the exhaust pipe

Causes

Oxygen sensor malfunction
Fuel leak
Dirty or faulty fuel injectors
Problems with the mass air flow sensor (MAF)
Engine management system malfunction

How to Fix

Check oxygen sensors
Check fuel injectors for contamination and functionality
Check the air flow sensor for contamination and malfunction
Check the engine management system for errors
Check the fuel system for leaks

Related codes

P21F6 P21F4 P21F7