Reductant Tank Temperature Sensor Circuit Issue
The P205A code indicates a problem in the reductant tank temperature sensor circuit, which is part of the Selective Catalytic Reduction (SCR) system. This sensor monitors the temperature of the diesel exhaust fluid (DEF) to ensure proper injection. A fault can cause incorrect DEF dosing, leading to increased emissions and potential damage to the SCR system.
1. Most Common Causes
- Faulty DEF tank temperature sensor (open circuit or internal short)
- Damaged, corroded, or shorted wiring/connectors in the signal or 5V reference circuit
- Internal failure of the DEF pump control module (if sensor is integrated)
- Low DEF level or contaminated fluid affecting thermal reading
- PCM failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased diesel exhaust fluid consumption
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the sensor and wiring for damage or corrosion.
Step 3: Test sensor resistance and compare to specifications.
Step 4: Check circuit continuity and voltage at the ECM connector.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can lead to reduced performance, increased emissions, and potential damage to the SCR system. Immediate diagnosis is advised.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause and vehicle model.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.