What Does P203D Mean?
The PCM detects the DEF level sensor signal voltage is above the maximum acceptable threshold. This indicates a short to power, open circuit, or sensor failure.
Common Causes
35%
Open circuit in DEF level sensor ground or signal wire
30%
Failed DEF level sensor with internal open circuit
20%
Short to voltage in sensor signal wire
15%
Corroded or disconnected sensor connector
Diagnostic Steps
1
Step 1: Inspect DEF level sensor connector for proper connection and terminal integrity
2
Step 2: With sensor connected, backprobe signal wire and verify voltage corresponds to actual tank level
3
Step 3: Disconnect sensor and check for battery voltage on signal wire (indicates short to power)
4
Step 4: Test ground circuit continuity from sensor to PCM ground
5
Step 5: If circuits test good, replace DEF level sensor and verify proper signal range
Estimated Repair Cost
$250 - $1,100
Parts + labor, varies by vehicle and location
The PCM detects the DEF level sensor signal voltage is above the maximum acceptable threshold. This indicates a short to power, open circuit, or sensor failure.
The most common cause of P203D (Reductant Level Sensor Circuit High) is: Open circuit in DEF level sensor ground or signal wire
Typical repair costs for P203D range from $250 to $1,100, depending on the vehicle, location, and whether you do it yourself or go to a shop.
System will read full or provide incorrect DEF level information. This may result in running out of DEF unexpectedly, causing vehicle operation restrictions per emissions laws.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P203D to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control (SCR System)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
