Code
P1215
KIA
P — Powertrain
Fuel Injector 3 Circuit High Voltage
AI status
Completed
Completed
100%
Causes
- Short to battery voltage on the injector 3 driver circuit
- Internal short or fault in the fuel injector (cylinder 3)
- Open or high-resistance wiring or connector (supply or driver side)
- Poor or corroded connector pins/ground connection
- Failed engine control module (injector driver output)
- Faulty related sensors or circuits causing abnormal driver behavior
Symptoms
- Malfunction Indicator Lamp (MIL) / check engine light ON
- Misfire, rough idle or poor cylinder 3 performance
- Reduced engine power, hesitation, or stumbling under load
- Poor fuel economy
- Possible hard start or no-start in severe cases
What to check
- Read and record freeze-frame and all stored codes; check for related misfire or injector codes (e.g., P0203, P0303).
- Visual inspection of injector 3 connector, wiring harness, and engine grounds for damage, corrosion, or heat damage.
- Perform a wiggle test while monitoring live data or injector status to reproduce the fault.
- Use a scan tool to perform an injector on/off command (if available) and monitor response.
- Measure supply voltage at injector connector and compare to battery voltage with key ON.
- Measure injector coil resistance and check for short to B+ or open to ECM.
Signal parameters
- Injector supply (battery feed) at injector connector: ~12 V (key ON/battery condition).
- Driver/low-side voltage when idle (ECM not commanding): should be near battery voltage on supply pin and near battery on driver pin (open/high) OR float; when commanded, driver should switch toward 0–1 V (ground) on low-side in most systems.
- Injector coil resistance: typically low (varies by model); expect ~1–16 Ω depending on high/low impedance type — compare to known-good spec for the vehicle.
- Injector pulse width: variable with engine load; observed waveform on scope should be a clean square/pulse with expected duty and no abnormal voltage spikes.
- Current draw when energized: typically in the amp range (commonly 1–5 A for many injectors) — large deviations suggest a fault.
Diagnostic algorithm
- Verify code with a scan tool, clear codes, and attempt to re-create; record freeze-frame data and note operating conditions when the code set.
- Inspect visually: connector, wiring harness routing, heat/chafing, pin corrosion, and engine grounds near cylinder 3. Repair any obvious damage.
- With ignition OFF, disconnect injector 3 connector and inspect pins for corrosion, bent pins, or pushed-out terminals. Reconnect and retest.
- Measure injector 3 coil resistance with an ohmmeter at the injector. Compare to specification. If resistance is abnormally low (short) or open, replace the injector.
- Back-probe the injector connector with ignition ON and engine cranking or commanded using a scan tool: verify constant battery feed on the supply pin and observe the driver pin. When ECU commands, driver should pull to ground (~0–1 V).
- Use an oscilloscope to view injector waveform while cranking/running. Look for high-voltage spikes, abnormal offsets, or no switching. High steady voltage or absence of pulsing suggests short/B+ or driver failure.
- Perform a swap test: exchange injector 3 with another cylinder's injector (if safe and practical) and see if the DTC or misfire follows the injector. If it follows, replace injector; if it stays on cylinder 3, suspect wiring or ECM.
- Check continuity and resistance between injector driver pin at ECM connector and the injector low-side pin; check for short to battery (B+) and for shorts to other circuits.
- If wiring and injector test good, bench-test or inspect ECM injector driver outputs. If driver is confirmed faulty, replace ECM per manufacturer procedure and reprogram if required.
- After repairs, clear codes and perform a road test to confirm the fault does not return.
Likely causes
- Damaged or pinched harness near injector 3 causing contact with B+
- Injector 3 coil internally shorted or seizing (higher than normal voltage when driven)
- Corroded or pushed-out connector pin at injector 3 causing intermittent high readings
- Aftermarket work or recent repairs with mis-routed or repaired wires
- Failed low-side driver transistor inside the PCM/ECM
Fault status
Status
Fuel Injector 3 Circuit High Voltage — ECM detected excessively high voltage on injector 3 drive circuit. Inspect injector, wiring, and driver.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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