What causes fault code P028C?

• Most likely: Short to battery voltage (B+) in the injector 10 wiring harness • Likely: Defective fuel injector (internal short circuit) • Possible: Corroded or damaged connector pins • Rare: Internal failure in the Engine Control Module (ECM)

How do you fix fault code P028C?

STEP 1: Visually inspect the wiring harness for injector 10. Look for frayed wires or melted insulation that could cause a short to power. Clean the connector. STEP 2: Measure resistance across the injector pins using a multimeter. At 20°C (68°F), resistance should typically be 10–16 Ohms (check OEM specs). Infinite or 0 Ohms means the injector is faulty. STEP 3: Voltage check: with ignition ON, check if the signal wire is shorted to 12V by measuring towards ground. STEP 4: Use an oscilloscope to view the injector pulse-width modulation (PWM). If the signal stays high constantly, replace the injector or repair the short circuit. STEP 5: Clear fault codes and perform a road test.

Powertrain (Engine & Gearbox)Standard EOBD

P028C - Cylinder 10 Injector Circuit High

Q: What are the symptoms of fault code P028C?

• Check engine light (MIL) illuminated • Engine misfire or rough idling • Reduced engine power and poor acceleration • Increased fuel consumption • Failed emissions test

Last updated:1 February 2026

Related:Fuel Injector Cylinder 10, Engine Control Module (ECM), Wiring/Wiring Harness, Fuel System Relay

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0200

Injector Circuit Malfunction

P0201

Cylinder 1 Injector Circuit Open

P0202

Injector Circuit - Cylinder 2 - Malfunction

P0203

Injector Circuit - Cylinder 3

Technical Description

P028C is set when the Engine Control Module (ECM) detects an abnormally high voltage within the fuel injector circuit for cylinder 10. This typically indicates a short to battery voltage (B+) in the wiring harness or an internal fault within the injector coil itself. The ECM monitors current flow and voltage drops during the injection cycle. If the voltage remains high when the injector should be grounded or closed, the diagnostic logic triggers the fault. This will likely result in a cylinder misfire or the ECM disabling the injector to prevent engine damage or emission component failure.

Possible Causes

Short to battery voltage (B+) in the injector 10 wiring harness

Defective fuel injector (internal short circuit)

Corroded or damaged connector pins

Internal failure in the Engine Control Module (ECM)

Symptoms

Check engine light (MIL) illuminated

Engine misfire or rough idling

Reduced engine power and poor acceleration

Increased fuel consumption

Failed emissions test

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P028C - Cylinder 10 Injector Circuit High

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P028C - Cylinder 10 Injector Circuit High

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