P21AB Code - Reductant Level Sensor 'B' Circuit High
Quick Answer
The Powertrain Control Module (PCM) monitors the reductant level sensor circuits to the PCM for high and low voltage. Common causes include Faulty Reductant Level Sensor, Reductant Level Sensor harness is open or shorted, Reductant Level Sensor circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
- What it means
- P21AB indicates Reductant Level Sensor 'B' Circuit High.
- Common causes
- Common causes include Faulty Reductant Level Sensor, Reductant Level Sensor harness is open or shorted, Reductant Level Sensor circuit poor electrical connection.
- Severity
- Moderate - service should be scheduled soon.
- Can I drive?
- The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Code P21AB Description
The reductant level sensor and reductant temperature sensor share a common ground. An open or short to voltage in this ground sets DTCs for both sensors.
What are the Possible Causes of the DTC P21AB?
- Faulty Reductant Level Sensor
- Reductant Level Sensor harness is open or shorted
- Reductant Level Sensor circuit poor electrical connection
How to Fix the DTC P21AB?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P21AB code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific Makes
- P21AB Chevrolet — Reductant Level Sensor 2 Circuit High Voltage
- P21AB Ford — Reductant Level Sensor 'B' Circuit High
- P21AB GMC — Reductant Level Sensor 2 Circuit High Voltage
Frequently Asked Questions about P21AB Code
What does the OBDII code P21AB mean?
The code P21AB indicates a problem with the reductant level sensor 'B' circuit, specifically that the circuit is reading a high signal, which may suggest an issue with the sensor itself or its wiring.
What are the common symptoms of the P21AB code?
Symptoms may include the check engine light being illuminated, reduced engine power, and possible warnings related to the emission control system.
What could cause the P21AB code to trigger?
Causes can include a faulty reductant level sensor, damaged wiring or connectors in the sensor circuit, low reductant fluid levels, or issues with the vehicle's engine control module (ECM).
How can I diagnose the P21AB code?
Begin by checking the reductant fluid level; if low, refill it. Then inspect the wiring and connectors for damage. Finally, use a multimeter to test the sensor’s resistance and voltage output.
What repairs are typically needed for the P21AB code?
Repairs may include replacing the reductant level sensor, repairing or replacing damaged wiring or connectors, or addressing any ECM issues if they are determined to be the cause.
Can I drive my vehicle with the P21AB code?
While it may be possible to drive the vehicle, doing so is not recommended as it may lead to reduced performance and could affect emissions compliance.
Is the P21AB code related to the diesel exhaust fluid (DEF) system?
Yes, the P21AB code is related to the DEF system, specifically monitoring the level of the reductant fluid used to reduce emissions in diesel engines.
How can I reset the P21AB code after repairs?
You can reset the code by using an OBDII scanner to clear the codes, or by disconnecting the vehicle's battery for a short period. However, ensure the underlying issue is resolved before doing this.
What is the likely cost of repairing the P21AB code?
Repair costs can vary widely based on the cause; replacing a sensor may cost between $100 to $300, while wiring repairs or ECM issues could be more expensive.
Are there any preventative measures to avoid the P21AB code?
Regularly check and maintain the DEF fluid levels, and ensure that the sensor and wiring are in good condition to help prevent triggering the P21AB code.
Discuss the causes and fixes for P21AB OBDII Code
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