P21B4
NOx Adsorber - Over Temperature Bank 1
P21B4 is an OBD-II diagnostic trouble code meaning: NOx Adsorber - Over Temperature Bank 1. Common causes: nox canister temperature sensor malfunction, problems with the adsorber regeneration system. Estimated repair cost: $56–278.
Symptoms
- Check Engine light comes on
- Reduced engine power
- Increased fuel consumption
- Unusual odors from the exhaust system
- Engine transition to emergency mode
Causes
- NOx canister temperature sensor malfunction
- Problems with the adsorber regeneration system
- Clogged or damaged NOx adsorber
- Malfunctions in the engine management system
- Problems with the wiring harness to the temperature sensor
How to Fix
- Check the readings of the NOx adsorber temperature sensor
- Inspect the NOx adsorber for damage
- Check the temperature sensor circuit for opens and shorts
- Conduct diagnostics of the adsorber regeneration system
- If necessary, replace the NOx adsorber or temperature sensor
Related codes
Error P21B4 by Vehicle Brand
FAQ
What does the P21B4 code mean?
P21B4 is an OBD-II diagnostic trouble code that indicates: NOx Adsorber - Over Temperature Bank 1
What causes a P21B4 error code?
The most common causes of P21B4 include: NOx canister temperature sensor malfunction; Problems with the adsorber regeneration system; Clogged or damaged NOx adsorber; Malfunctions in the engine management system.
How do I fix a P21B4 diagnostic trouble code?
To fix P21B4: Check the readings of the NOx adsorber temperature sensor. Inspect the NOx adsorber for damage. Check the temperature sensor circuit for opens and shorts. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21B4?
Yes, but get it checked soon
How much does it cost to fix P21B4?
The estimated repair cost for P21B4 is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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