The P20AE: Reductant Metering Unit Temperature Sensor Circuit Low fault code indicates that the circuit for the reductant metering unit temperature sensor is experiencing low voltage. This sensor monitors the temperature of the diesel exhaust fluid (DEF) to ensure proper dosing. Low voltage in the circuit can result in incorrect sensor readings, potentially affecting the DEF injection process. This issue may be caused by a faulty sensor, wiring issues, or a problem within the sensor circuit.
P20AE – Quick Overview
Code | Information |
---|---|
Meaning | P20AE: Reductant Metering Unit Temperature Sensor Circuit Low |
Is it serious? | Yes, it can affect proper DEF dosing, which may lead to emissions control issues and increased emissions. |
Possible causes | – Low 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 |
P20AE Meaning
The P20AE code indicates that the voltage in the reductant metering unit temperature sensor circuit is lower than expected. This sensor is responsible for monitoring the temperature of DEF to ensure it is injected at the correct temperature. Low voltage can lead to inaccurate sensor readings, affecting the performance of the DEF injection system and possibly causing higher emissions.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for additional related fault codes that may help provide more insight into the issue with the sensor or 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 the manufacturer’s specifications to confirm low voltage. | Multimeter |
Test the Reductant Metering Unit Temperature Sensor | Use a diagnostic tool or multimeter to test the sensor’s functionality and ensure it is operating within the correct 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 disconnections that could cause low 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 P20AE code does not return. If the code reappears, further diagnostics may be required. | OBD-II Scanner |

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