What Does P20B0 Mean?
The reductant metering unit temperature sensor is providing unstable or inconsistent readings that fluctuate outside normal parameters. This indicates intermittent electrical connections, sensor degradation, or signal interference in the DEF temperature monitoring circuit.
Common Causes
35%
Loose or intermittent connection at sensor connector or ECM
25%
Damaged wiring harness with intermittent short or open
20%
Failing temperature sensor with intermittent internal fault
15%
Corrosion or moisture in sensor connector causing intermittent contact
5%
Electromagnetic interference from damaged shielding or routing near high-current wires
Diagnostic Steps
1
Step 1: Wiggle test all connectors and wiring while monitoring sensor data on scan tool to identify intermittent fault location
2
Step 2: Inspect connector terminals for corrosion, looseness, or improper terminal tension
3
Step 3: Check wiring harness routing for contact with hot exhaust components or sharp edges that may cause intermittent grounding
4
Step 4: Monitor sensor resistance values while applying heat/cold to sensor body to check for internal intermittent fault
5
Step 5: Replace sensor if no wiring issues found; secure and reroute harness if chafing detected
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The reductant metering unit temperature sensor is providing unstable or inconsistent readings that fluctuate outside normal parameters. This indicates intermittent electrical connections, sensor degradation, or signal interference in the DEF temperature monitoring circuit.
The most common cause of P20B0 (Reductant Metering Unit Temperature Sensor Circuit Intermittent/Erratic) is: Loose or intermittent connection at sensor connector or ECM
Typical repair costs for P20B0 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent faults may cause unpredictable power reduction events. May lead to emissions system malfunction and eventual vehicle derate if not corrected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P20B0 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System (SCR)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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