OBD Guide

P221A

NOx Sensor 1/2 Correlation Bank 1

P221A is an OBD-II diagnostic trouble code meaning: NOx Sensor 1/2 Correlation Bank 1. Common causes: nox sensor 1 or 2 malfunction, damage to the sensor wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine light comes on
  • Reduced engine power
  • Increased fuel consumption
  • Problems with passing inspection due to emissions

Causes

  • NOx sensor 1 or 2 malfunction
  • Damage to the sensor wiring harness
  • Problems with sensor connectors
  • Engine control unit malfunction
  • Software error in the control system

How to Fix

  1. Check fault codes in the ECU memory
  2. Inspect the connection and wiring harness of the NOx sensors
  3. Check the operation of NOx sensors using diagnostic equipment
  4. Replace faulty NOx sensor if necessary
  5. Update ECU software if required

Related codes

Error P221A by Vehicle Brand

FAQ

What does the P221A code mean?

P221A is an OBD-II diagnostic trouble code that indicates: NOx Sensor 1/2 Correlation Bank 1

What causes a P221A error code?

The most common causes of P221A include: NOx sensor 1 or 2 malfunction; Damage to the sensor wiring harness; Problems with sensor connectors; Engine control unit malfunction.

How do I fix a P221A diagnostic trouble code?

To fix P221A: Check fault codes in the ECU memory. Inspect the connection and wiring harness of the NOx sensors. Check the operation of NOx sensors using diagnostic equipment. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P221A?

Yes, but get it checked soon

How much does it cost to fix P221A?

The estimated repair cost for P221A is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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