P21AB Ford 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 Ford 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 Ford 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 Ford?
- 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 Ford?
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 Ford 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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Frequently Asked Questions about P21AB Ford Code
1. What does the OBDII code P21AB mean on a Ford vehicle?
P21AB indicates a high voltage issue in the Reductant Level Sensor 'B' Circuit, which monitors the DEF (Diesel Exhaust Fluid) level in the tank.
2. What are the common symptoms of the P21AB code?
Symptoms include a check engine light, DEF system warnings, reduced engine performance, or the vehicle entering limp mode in severe cases.
3. What causes the P21AB code to trigger?
Common causes include a faulty DEF level sensor, damaged wiring or connectors, a malfunctioning powertrain control module (PCM), or contamination in the DEF tank.
4. How can I diagnose the P21AB code?
Start by checking the wiring and connectors for damage or corrosion, inspect the DEF tank for contamination, and test the DEF level sensor for proper functionality.
5. Can I still drive my Ford with a P21AB code?
While the vehicle may still be drivable initially, ignoring this code can lead to reduced performance or limp mode as the DEF system is essential for emissions compliance.
6. How is the P21AB code fixed?
Repairs may involve replacing the DEF level sensor, repairing damaged wiring, cleaning the DEF tank, or updating/reprogramming the PCM if necessary.
7. How much does it cost to fix the P21AB code?
Repair costs vary depending on the issue but typically range from $150 to $500, including parts and labor.
8. Can a P21AB code be caused by bad DEF fluid?
Yes, contaminated or low-quality DEF fluid can cause issues with the level sensor, leading to this code.
9. Does the P21AB code affect emissions compliance?
Yes, the code directly relates to the DEF system, which is critical for reducing nitrogen oxide emissions in diesel vehicles.
10. Can I clear the P21AB code without fixing the issue?
Clearing the code without addressing the underlying problem will likely cause it to return and may exacerbate DEF system issues over time.
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