Code
P20CE
Generic
P — Powertrain
Exhaust Aftertreatment Fuel Injector A Control Circuit High
Views:
UK: 22
EN: 29
RU: 23
AI status
Completed
Completed
100%
Causes
- Short to battery or constant power on the injector control wire
- Faulty exhaust aftertreatment fuel injector (internal short or internal open causing abnormal voltage)
- Corroded, damaged, or poorly seated connector/pins at the injector or wiring harness
- Damaged wiring harness (chafing, pinched, damaged insulation) causing intermittent/high voltage
- Poor or missing ground(s) related to the injector circuit or controller
- Faulty engine control module (ECM) or aftertreatment control module driver
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Aftertreatment regeneration failure or incomplete forced regeneration
- Reduced engine performance or entry to limp mode if ECU restricts operation
- Repeated regeneration attempts or DPF/burner errors logged
- Possible fuel smell or abnormal exhaust behavior during attempted regeneration
- Stored related aftertreatment or injector DTCs with freeze-frame data
What to check
- Retrieve freeze-frame and full DTC list with a capable scan tool; note conditions when P20CE set
- Visually inspect injector A connector, pins and harness for corrosion, bent pins, damage, or water intrusion
- Inspect wiring along the harness for chafing, pinching, or repairs/splices that could short to battery
- Check related fuses, relays, and supply circuits feeding the injector system
- Backprobe the injector A connector with key ON (engine OFF) and command ON with scan tool while watching live data
- Measure supply voltage at the injector harness (expect battery voltage at supply pin ~11–14.5 V) and measure control/driver pin behavior when commanded
Signal parameters
- Typical supply voltage to injector: ~11–14.5 V (battery nominal range)
- Injector coil/solenoid resistance: manufacturer specific (typical range for similar solenoids 1–50 Ω — check service data)
- Control/driver signal when commanded: pulsed or switched (0–battery voltage) depending on driver design; expect pulsed voltage or a low-side pull to ground when active
- High condition definition: control circuit seen at a voltage higher than expected off-state or stuck near battery voltage when driver should be pulling it low (exact threshold varies by controller)
- Diagnostic tool should show command state (ON/OFF), current draw/pulse duty and any driver status/fault flags
Diagnostic algorithm
- Read and record all stored codes and freeze-frame data. Note recent freeze-frame conditions (RPM, temp, voltage, load).
- Perform a thorough visual inspection of harness, connectors, and grounds for injector A. Repair obvious damage before further testing.
- With key ON (engine OFF), backprobe connector and measure supply and control pins for correct battery presence and expected rest voltages. Compare to known-good circuits if available.
- Command the injector ON with a scan tool while watching the control pin. Observe whether the driver pulls the circuit low or pulses as expected. If control stays high/unresponsive, suspect short to power or driver fault.
- Measure injector resistance and compare to spec. If out of spec, replace injector. If in spec, check for short to battery: disconnect injector and measure resistance from control circuit to battery positive and to ground.
- If a short to battery is present with injector disconnected, trace and repair wiring to remove short (repair chafe, replace harness, correct splices).
- If wiring checks OK and injector behaves correctly on bench test or when swapped with a known-good injector, suspect ECM/aftertreatment module driver — verify with manufacturer diagnostics before replacing module.
- After repairs, clear codes and perform a forced regeneration or drive cycle to confirm fault does not return. Monitor live data for proper injector operation.
- If intermittent, flex wiring, recheck over temperature cycles, and consider protective routing or harness replacement to prevent recurrence.
Likely causes
- Short to battery on injector A control circuit (most common)
- Corroded/incomplete connector at injector A
- Failed injector solenoid or internal wiring fault
- Open/failed ground for the injector driver or controller
- Intermittent wiring damage (chafe) causing high-voltage feedback to the controller
Fault status
Status
Control circuit high detected for Exhaust Aftertreatment Fuel Injector A — the injector drive circuit is seeing an abnormally high voltage (possible short to battery or wiring/connector fault). May prevent proper aftertreatment dosing and cause regeneration failures.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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