The P202B: Reductant Tank Heater Control Circuit Low indicates a low voltage condition in the control circuit of the reductant tank heater. This could be caused by a faulty heater control unit, low voltage in the circuit, or issues with wiring and connectors.
P202B – Quick Overview
| Code | Information |
|---|---|
| Meaning | P202B: Reductant Tank Heater Control Circuit Low |
| Is it serious? | Yes, low voltage can prevent the reductant tank heater from working, which can cause the DEF (Diesel Exhaust Fluid) to freeze in cold weather, affecting the emission system. |
| Possible causes | – Low voltage in the heater control circuit – Faulty heater control – Wiring or connector issues |
| How to diagnose? | – Measure voltage in the heater control circuit – Test the heater control unit – Inspect wiring and connectors |
P202B Meaning
The P202B: Reductant Tank Heater Control Circuit Low code indicates that the voltage in the reductant tank heater control circuit is lower than the manufacturer’s specified range. The reductant tank heater is responsible for warming the DEF tank in cold conditions, ensuring proper emission control operation. A low voltage condition may prevent the heater from working effectively, leading to DEF freezing and system malfunction.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for additional related codes. These may provide more context for diagnosing the issue with the reductant system or heater. | OBD-II Scanner |
| Measure Voltage in the Heater Control Circuit | Use a multimeter to measure the voltage in the reductant tank heater control circuit. Compare the voltage reading to the manufacturer’s specifications to confirm if it is too low. | Multimeter |
| Test the Heater Control Unit | Use a diagnostic tool to test the heater control unit and verify that it is functioning correctly. A faulty control unit may be supplying insufficient voltage to the heater. | Diagnostic Tool, Multimeter |
| Inspect Wiring and Connectors | Visually inspect the wiring and connectors leading to the reductant tank heater and control unit. Look for corrosion, damage, or loose connections that may cause low voltage in the circuit. | Flashlight, Multimeter |
| Test Circuit Continuity | Perform a continuity test on the wiring to ensure there are no breaks, shorts, or high resistance causing the low voltage condition. | Multimeter |
| Inspect the Reductant Tank Heater | Inspect the reductant tank heater for proper operation. If it is not functioning or drawing too much power, it may need to be replaced. | Diagnostic Tool, Flashlight |
| Repair or Replace Damaged Components | If any damaged wiring, connectors, or faulty components are found, repair or replace them to restore proper voltage to the heater control circuit. | Wiring Repair Kit, Heater Replacement Kit |
| Clear the Code and Test Drive | After completing repairs, clear the P202B code using an OBD-II scanner. Test the vehicle and monitor the reductant tank heater operation to ensure the issue has been resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
| Recheck for Codes | After the test drive, re-scan the vehicle to confirm that the P202B code has not returned. | OBD-II Scanner |
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