[SOLVED] P21B2 Code: Fixing Slow Nox Absorber Control Loop

If you’re experiencing an illuminated Engine Light or Service Engine Soon Warning Light, it could be due to the P21B2 fault code. This code indicates that the Mass Air Flow (MAF) Sensor value has not been learned, the EGR valve is sticking or restricted, the thermostat outlet is restricted, or there is a faulty EGR cooler bypass control valve or EGR airflow control valve.

Another possible cause could be a leaking or damaged NOx absorber catalyst. The importance of repairing this issue lies in the fact that it can negatively impact your vehicle’s performance and fuel efficiency.

The repair difficulty is moderate, with an estimated repair time of 1.0 hour. To fix the issue, you should visually inspect the related wiring harness and connectors, check for damaged components, and look for broken, bent, pushed out, or corroded connector’s pins.

Repair Importance Level10.0 (Out of 10)
Estimated Repair TimeApproximately 1.0 hour
Repair Difficulty Level10.0 (Out of 10)

If you notice the Engine Light ON or Service Engine Soon Warning Light, it could be a sign of p21b2 fault code.

Here are the symptoms to look out for:

  • The P21B2 fault code in automobiles can cause several symptoms, including the engine light turning on or the service engine soon warning light appearing.
  • Other symptoms may include reduced engine power, decreased fuel efficiency, rough idling, stalling, and difficulty starting the engine.
  • Additionally, the vehicle may experience transmission shifting issues, and the driver may notice a decrease in overall performance.
  • It is important to address these symptoms promptly to prevent further damage to the vehicle.

The P21B2 automobile fault code can be caused by various factors, including MAF sensor value, EGR valve, thermostat outlet, EGR cooler bypass control valve, EGR airflow control valve, and NOx absorber catalyst.

  • The automobile fault code P21B2 can be caused by several factors.
  • These include the Mass Air Flow (MAF) Sensor value not learned, a sticking or restricted EGR valve, a restricted thermostat outlet, a faulty EGR cooler bypass control valve, a faulty EGR airflow control valve, and a leaking or damaged NOx absorber catalyst.
  • It is important to identify the specific cause of the fault code in order to properly address and fix the issue.

To fix the p21b2 automobile fault code, check the possible causes and inspect related wiring harness and connectors for damage.

  • To fix the automobile fault code P21B2, first, check the possible causes listed above.
  • Then, visually inspect the related wiring harness and connectors.
  • Look for any damaged components and check for broken, bent, pushed out, or corroded connector’s pins.
  • This fix will take an estimated repair time of 1.0 hour.

The factors that influence the cost of fixing the automobile fault code P21B2 are the estimated repair time and the hourly rate charged by the auto repair shop.

The estimated repair time for this fault code is 1.0 hour. The cost of fixing the fault code will depend on the hourly rate charged by the auto repair shop, which is typically between $75 and $150 per hour.

These factors should be considered when estimating the cost of fixing the P21B2 fault code.

The P21B2 fault code is related to the DeNOx mode of the engine. The Powertrain Control Module (PCM) monitors the post-injection fuel and O2 Sensor 11 value. If the O2 Sensor 11 value is high for a calibrated time, the fail counter is incremented.

If the counter value is greater than a calibrated value, the P21B2 fault code is set. This fault code indicates excessive time to enter closed loop NOx absorber control.

What are the possible causes of the P21B2 fault code?

If you’re experiencing the P21B2 fault code, you may notice that your engine light is on. This could be due to a variety of causes, including a Mass Air Flow (MAF) Sensor value that hasn’t been learned, a sticking or restricted EGR valve, a restricted thermostat outlet, a faulty EGR cooler bypass control valve, a faulty EGR airflow control valve, or a leaking or damaged NOx absorber catalyst. To fix the issue, it’s important to check the possible causes listed above and visually inspect the related wiring harness and connectors for any damage or corrosion.

How can I fix the P21B2 fault code?

If you’re experiencing the P21B2 fault code, indicated by the engine light or service engine soon warning light, it may be due to a Mass Air Flow (MAF) Sensor value not learned, a sticking or restricted EGR valve, a restricted thermostat outlet, a faulty EGR cooler bypass control valve, a faulty EGR airflow control valve, or a leaking or damaged NOx absorber catalyst. To fix it, check the possible causes listed above, visually inspect the related wiring harness and connectors, and look for damaged components or connector pins.

Is it necessary to visually inspect the wiring harness and connectors to fix the P21B2 fault code?

To fix the P21B2 fault code, it is necessary to visually inspect the related wiring harness and connectors. The fault code can be caused by various factors such as a faulty EGR valve, a restricted thermostat outlet, or a leaking NOx absorber catalyst. However, the root cause may be a Mass Air Flow (MAF) Sensor value not learned or a faulty EGR cooler bypass control valve. Therefore, it is important to check the possible causes listed above and visually inspect the wiring harness and connectors for any damage or corrosion.

p21b2 error fault code explained

If you see the Engine Light ON or Service Engine Soon Warning Light due to P21B2, check the MAF sensor value, EGR valve, thermostat outlet, EGR cooler bypass control valve, EGR airflow control valve, and NOx absorber catalyst.

Inspect the wiring harness and connectors for damage and corrosion. Look for broken, bent, or pushed out connector pins.

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