What Does P20D1 Mean?
The PCM has detected an open circuit or electrical fault in the control circuit for exhaust aftertreatment fuel injector B. This injector is used to inject fuel into the exhaust stream for diesel particulate filter (DPF) regeneration or SCR system operation.
Common Causes
35%
Wiring harness damage, corrosion, or connector issues in injector B control circuit
30%
Faulty exhaust fuel injector B internal coil or solenoid failure
20%
PCM internal driver circuit failure for injector B
10%
Blown fuse or open relay in injector control circuit
5%
Poor ground connection at injector or PCM
Diagnostic Steps
1
Step 1: Visually inspect exhaust fuel injector B connector and wiring for damage, corrosion, or loose connections
2
Step 2: Measure resistance of injector B coil (typically 2-10 ohms depending on manufacturer spec)
3
Step 3: Check for battery voltage at injector connector with key on, engine off
4
Step 4: Use multimeter to verify ground circuit continuity to PCM
5
Step 5: Check relevant fuses and relays in the exhaust aftertreatment fuel system
6
Step 6: Perform PCM driver circuit test by commanding injector on with scan tool and monitoring voltage
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The PCM has detected an open circuit or electrical fault in the control circuit for exhaust aftertreatment fuel injector B. This injector is used to inject fuel into the exhaust stream for diesel particulate filter (DPF) regeneration or SCR system operation.
The most common cause of P20D1 (Exhaust Aftertreatment Fuel Injector "B" Control Circuit/Open) is: Wiring harness damage, corrosion, or connector issues in injector B control circuit
Typical repair costs for P20D1 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains drivable but DPF regeneration will be impaired, potentially leading to exhaust system damage and derate conditions if not repaired. No immediate safety risk to occupants.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P20D1 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Exhaust Aftertreatment System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
