The P20AF: Reductant Metering Unit Temperature Sensor Circuit High fault code indicates that the circuit for the reductant metering unit temperature sensor is experiencing higher-than-expected voltage. This sensor is responsible for monitoring the temperature of the diesel exhaust fluid (DEF) to ensure it is injected at the correct temperature for proper emissions control. High voltage in this circuit can lead to inaccurate readings and improper DEF dosing, affecting emissions system performance. This issue may be caused by a faulty sensor, wiring problems, or connector issues.
P20AF – Quick Overview
| Code | Information |
|---|---|
| Meaning | P20AF: Reductant Metering Unit Temperature Sensor Circuit High |
| Is it serious? | Yes, it can cause improper DEF dosing, leading to emissions control problems and higher emissions. |
| Possible causes | – High voltage in the temperature sensor circuit – Faulty temperature sensor – Wiring or connector issues |
| How to diagnose? | – Measure voltage in the temperature sensor circuit – Test the reductant metering unit temperature sensor – Inspect wiring and connectors |
P20AF Meaning
The P20AF code indicates that the voltage in the reductant metering unit temperature sensor circuit is higher than expected. This temperature sensor ensures that the DEF is injected at the proper temperature for optimal performance of the emissions system. High voltage in this circuit can lead to inaccurate readings, which may disrupt the DEF dosing process and increase emissions.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for additional related codes that could provide further context on the issue with the DEF system. | OBD-II Scanner |
| Measure Voltage in the Circuit | Use a multimeter to measure the voltage in the temperature sensor circuit and compare it to manufacturer specifications to confirm high voltage. | Multimeter |
| Test the Reductant Metering Unit Temperature Sensor | Use a diagnostic tool or multimeter to test the sensor’s functionality to ensure it is operating within the proper voltage range. | Multimeter, Diagnostic Tool |
| Inspect Wiring and Connectors | Visually inspect the wiring and connectors leading to the temperature sensor for signs of damage, corrosion, or loose connections that could cause high voltage. | Flashlight, Multimeter |
| Clear the Code and Test Drive | After completing repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to ensure the issue has been resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
| Recheck for Codes | Re-scan the system after the test drive to ensure that the P20AF code does not return. If the code reappears, further diagnostics may be required. | OBD-II Scanner |
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