P21F9

Fuel Control System B Too Rich at Idle Bank 1

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$17–89 (est.)

Symptoms

Increased fuel consumption
Unstable engine idling
Black smoke from the exhaust pipe
Gasoline smell from exhaust
Fouled spark plugs

Causes

Oxygen sensor malfunction
Contamination or malfunction of the air flow sensor
Fuel leakage through injectors
Increased pressure in the fuel rail
Problems with the EVAP system

How to Fix

Check oxygen sensor readings
Clean or replace the mass air flow sensor
Check the tightness of the injectors
Measure the pressure in the fuel system
Check EVAP system for leaks

Related codes

P2177 P2187 P2195