P21F4

Fuel Control System B Too Lean Off Idle Bank 1

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$17–89 (est.)

Symptoms

Reduced engine power
Increased fuel consumption
Unstable engine operation
Check Engine Light Illuminates
Possible misfires

Causes

Vacuum leak in the intake system
Malfunction of the mass air flow sensor (MAF)
Dirty or faulty fuel injectors
Low fuel pressure due to faulty fuel pump
Oxygen sensor malfunction

How to Fix

Check the intake system for vacuum leaks
Check the MAF readings and replace if necessary
Clean or replace fuel injectors
Check fuel pressure and condition of the fuel pump
Check the operation of the oxygen sensor

Related codes

P2177 P2187 P2195