What Does P205C Mean?
The DEF tank temperature sensor circuit voltage is reading lower than the minimum acceptable threshold. This typically indicates a short to ground in the circuit or a sensor that is reading excessively cold temperatures.
Common Causes
35%
Short to ground in sensor wiring harness
30%
Failed DEF tank temperature sensor internally shorted
20%
Damaged or pinched wires causing intermittent ground contact
10%
Corroded sensor connector creating ground path
5%
ECM internal short or faulty sensor circuit
Diagnostic Steps
1
Step 1: Disconnect DEF tank temperature sensor and measure resistance to ground on both sensor and harness sides
2
Step 2: Check for pinched or damaged wiring along entire harness run, especially near sharp edges
3
Step 3: Inspect sensor connector pins for corrosion or moisture causing short circuit
4
Step 4: Measure sensor resistance and verify it falls within specified range for ambient temperature
5
Step 5: If wiring and connections test good, replace sensor and clear codes
Estimated Repair Cost
$150 - $550
Parts + labor, varies by vehicle and location
The DEF tank temperature sensor circuit voltage is reading lower than the minimum acceptable threshold. This typically indicates a short to ground in the circuit or a sensor that is reading excessively cold temperatures.
The most common cause of P205C (Reductant Tank Temperature Sensor Circuit Low) is: Short to ground in sensor wiring harness
Typical repair costs for P205C range from $150 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but may experience power reduction. DEF system warnings will appear and continued operation may result in no-start condition.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P205C to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control (SCR/DEF System)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
