P21F4
Fuel Control System B Too Lean Off Idle Bank 1
P21F4 is an OBD-II diagnostic trouble code meaning: Fuel Control System B Too Lean Off Idle Bank 1. Common causes: vacuum leak in the intake system, malfunction of the mass air flow sensor (maf). Estimated repair cost: $17–89.
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
Error P21F4 by Vehicle Brand
FAQ
What does the P21F4 code mean?
P21F4 is an OBD-II diagnostic trouble code that indicates: Fuel Control System B Too Lean Off Idle Bank 1
What causes a P21F4 error code?
The most common causes of P21F4 include: 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.
How do I fix a P21F4 diagnostic trouble code?
To fix P21F4: Check the intake system for vacuum leaks. Check the MAF readings and replace if necessary. Clean or replace fuel injectors. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21F4?
Yes, but get it checked soon
How much does it cost to fix P21F4?
The estimated repair cost for P21F4 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat