OBD Guide

P21A1

Cylinder 6 Air-Fuel Ratio Imbalance

P21A1 is an OBD-II diagnostic trouble code meaning: Cylinder 6 Air-Fuel Ratio Imbalance. Common causes: dirty or faulty injectors, air leak in intake manifold. Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–89 (est.)

Symptoms

  • Uneven engine operation
  • Power reduction
  • Increased fuel consumption
  • Dips during acceleration
  • Check Engine Light Is On

Causes

  • Dirty or faulty injectors
  • Air leak in intake manifold
  • Problems with the oxygen sensor
  • Ignition coil malfunction
  • Low cylinder compression

How to Fix

  1. Check the condition of the fuel injectors
  2. Diagnose intake tract leaks
  3. Check the operation of oxygen sensors
  4. Test the ignition coil and spark plugs
  5. Measure the compression in the cylinder

Related codes

Error P21A1 by Vehicle Brand

FAQ

What does the P21A1 code mean?

P21A1 is an OBD-II diagnostic trouble code that indicates: Cylinder 6 Air-Fuel Ratio Imbalance

What causes a P21A1 error code?

The most common causes of P21A1 include: Dirty or faulty injectors; Air leak in intake manifold; Problems with the oxygen sensor; Ignition coil malfunction.

How do I fix a P21A1 diagnostic trouble code?

To fix P21A1: Check the condition of the fuel injectors. Diagnose intake tract leaks. Check the operation of oxygen sensors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21A1?

Yes, but get it checked soon

How much does it cost to fix P21A1?

The estimated repair cost for P21A1 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat