Code
P20D2
Generic
P — Powertrain
Exhaust Aftertreatment Fuel Injector B Control Performance
Views:
UK: 19
EN: 22
RU: 23
AI status
Completed
Completed
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Causes
- Open or short in injector B wiring (power, ground, or control)
- Poor connector or corrosion at injector/ECM harness
- Failed exhaust aftertreatment fuel injector B (stuck, clogged, or electrically open/shorted)
- Faulty ECM injector driver or internal control module fault
- Insufficient fuel supply to the injector (blocked line, failed pump or filter)
- Software issue or missing ECM calibration/parameter
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Failed or incomplete DPF/SCR regeneration events
- Aftertreatment system fault warnings or reduced system functionality
- Increased soot accumulation, higher exhaust emissions, or limp-home modes
- Possible abnormal engine run during forced regen attempts (roughness or smoke)
What to check
- Read and record all stored DTCs, freeze-frame data and pending codes
- Check for Technical Service Bulletins (TSBs) or calibration updates for this code
- Visually inspect injector B connector, wiring harness and route for damage or heat exposure
- Check fuses and relays for aftertreatment fuel injector circuits
- Measure supply voltage to the injector connector with ignition on
- Measure injector coil resistance and compare to specification
Signal parameters
- Typical control: low-side driver (switch to ground) with PWM duty control; check service manual for exact topology
- Expected command: 0–100% duty cycle depending on dosing requirements (ECM commanded)
- Nominal control voltage at connector: battery voltage (~12 V) on supply pin with ignition on
- Ground continuity: near 0 ohms between injector ground pin and vehicle chassis ground
- Injector coil resistance: compare to manufacturer spec (common range often tens to hundreds of ohms — check service data)
- PWM frequency: varies by vehicle (commonly tens to hundreds of Hz); verify with oscilloscope against OEM spec
Diagnostic algorithm
- Connect a compliant scan tool. Read and save DTCs, freeze frame and readiness status. Note operating conditions when fault set.
- Check for available ECM software updates or TSBs that address injector control faults.
- Perform a visual inspection of harness and connectors for injector B. Repair any damaged wiring, bent pins or corrosion.
- Verify power and ground presence at the injector connector with ignition ON. Repair fuses/relays or supply circuit faults.
- Measure injector coil resistance (engine off, connector disconnected). Compare to service specification. Replace if out of tolerance.
- Backprobe the control and supply pins. Command the injector on with a capable scan tool and observe voltage/duty. Confirm expected response.
- Use an oscilloscope to check the control waveform while the injector is commanded. Look for proper PWM shape, amplitude, and no excessive noise or shorted waveform.
- Check continuity between injector pins and ECM pins to rule out intermittent opens or shorts (wiggle test while monitoring).
- If wiring and injector check OK, perform an ECM driver test if supported. If driver output is absent or abnormal while command present, suspect ECM fault.
- If available, swap with a known-good injector (or swap driver outputs per OEM guidance) to isolate injector vs ECM. Replace the faulty component.
- After repair, clear codes and perform forced regeneration or drive cycle to confirm fault does not return.
Likely causes
- Damaged insulation or chafed wire causing intermittent short to ground or battery
- Connector pins pushed out, bent, corroded, or contaminated
- Injector solenoid coil out of specified resistance range or intermittent
- ECM output transistor (low-side driver) failed
- Plugged injector nozzle preventing proper spray and altering electrical load
- Fuse or relay for injector power circuit open or intermittent
Fault status
Status
Exhaust Aftertreatment Fuel Injector B control performance fault — ECM detected out-of-range response or improper signal from the injector control circuit.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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