OBD Guide

P21F5

Fuel Control System B Too Rich Off Idle Bank 1

P21F5 is an OBD-II diagnostic trouble code meaning: Fuel Control System B Too Rich Off Idle Bank 1. Common causes: oxygen sensor malfunction, fuel leak. Estimated repair cost: $17–89.

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

  1. Check oxygen sensors
  2. Check fuel injectors for contamination and functionality
  3. Check the air flow sensor for contamination and malfunction
  4. Check the engine management system for errors
  5. Check the fuel system for leaks

Related codes

Error P21F5 by Vehicle Brand

FAQ

What does the P21F5 code mean?

P21F5 is an OBD-II diagnostic trouble code that indicates: Fuel Control System B Too Rich Off Idle Bank 1

What causes a P21F5 error code?

The most common causes of P21F5 include: Oxygen sensor malfunction; Fuel leak; Dirty or faulty fuel injectors; Problems with the mass air flow sensor (MAF).

How do I fix a P21F5 diagnostic trouble code?

To fix P21F5: Check oxygen sensors. Check fuel injectors for contamination and functionality. Check the air flow sensor for contamination and malfunction. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21F5?

Yes, but get it checked soon

How much does it cost to fix P21F5?

The estimated repair cost for P21F5 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat