OBD Guide
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P21B5

NOx Adsorber - Over Temperature Bank 2

P21B5 is an OBD-II diagnostic trouble code meaning: NOx Adsorber - Over Temperature Bank 2. Common causes: nox canister temperature sensor malfunction, problems with the adsorber regeneration system. Estimated repair cost: $167–556.

Severity
🔴 High
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$167–556 (est.)

Symptoms

  • Check Engine light comes on
  • Reduced engine power
  • Increased fuel consumption
  • Unusual odors from the exhaust system
  • Dips during acceleration

Causes

  • NOx canister temperature sensor malfunction
  • Problems with the adsorber regeneration system
  • Exhaust system clogged
  • Engine control fault
  • Mechanical damage to the NOx adsorber

How to Fix

  1. Check the readings of the NOx adsorber temperature sensor
  2. Diagnose the adsorber regeneration system
  3. Check the exhaust system for blockages
  4. Scan the engine ECU for related errors
  5. If necessary, replace the NOx adsorber

Related codes

P21B4P21B6P21B7

Error P21B5 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P21B5 code mean?

P21B5 is an OBD-II diagnostic trouble code that indicates: NOx Adsorber - Over Temperature Bank 2

What causes a P21B5 error code?

The most common causes of P21B5 include: NOx canister temperature sensor malfunction; Problems with the adsorber regeneration system; Exhaust system clogged; Engine control fault.

How do I fix a P21B5 diagnostic trouble code?

To fix P21B5: Check the readings of the NOx adsorber temperature sensor. Diagnose the adsorber regeneration system. Check the exhaust system for blockages. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21B5?

Limited driving only, diagnose soon

How much does it cost to fix P21B5?

The estimated repair cost for P21B5 is $167–556. Actual cost depends on your vehicle, location, and labor rates.

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