OBD Guide

P21AF

Reductant Level Sensor C Circuit Low

P21AF is an OBD-II diagnostic trouble code meaning: Reductant Level Sensor C Circuit Low. Common causes: faulty reductant level sensor c, open or short circuit in the sensor circuit. Estimated repair cost: $33–89.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$33–89 (est.)

Symptoms

  • Check Engine light comes on
  • Increased emissions of harmful substances
  • Possible engine power limitation
  • Incorrect reductant level readings
  • Error message in the SCR system

Causes

  • Faulty reductant level sensor C
  • Open or short circuit in the sensor circuit
  • Poor connection or corrosion in connectors
  • Problems with the engine control unit (ECU)
  • Low level of reductant in the tank

How to Fix

  1. Check the reductant level in the tank
  2. Inspect the sensor wiring and connectors for damage
  3. Check sensor resistance and voltage to specifications
  4. Replace the faulty reductant level sensor if necessary
  5. Reset the error code and check if it returns

Related codes

Error P21AF by Vehicle Brand

FAQ

What does the P21AF code mean?

P21AF is an OBD-II diagnostic trouble code that indicates: Reductant Level Sensor C Circuit Low

What causes a P21AF error code?

The most common causes of P21AF include: Faulty reductant level sensor C; Open or short circuit in the sensor circuit; Poor connection or corrosion in connectors; Problems with the engine control unit (ECU).

How do I fix a P21AF diagnostic trouble code?

To fix P21AF: Check the reductant level in the tank. Inspect the sensor wiring and connectors for damage. Check sensor resistance and voltage to specifications. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P21AF?

Yes, but get it checked soon

How much does it cost to fix P21AF?

The estimated repair cost for P21AF is $33–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat