Code
P1216
PORSCHE
P — Powertrain
Fuel injector, cylinder 4
Views:
UK: 5
EN: 14
RU: 7
AI status
Completed
Completed
100%
Causes
- Open or shorted injector coil (cylinder 4)
- Corroded, loose or damaged connector or wiring to injector 4
- Faulty PCM/ECM driver for injector 4
- Poor ground or low battery/rail voltage
- Clogged or mechanically failed injector (stuck open/closed)
- Low rail fuel pressure or failing fuel pump/regulator
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Rough idle or engine runs unevenly
- Misfire on cylinder 4 (reduced power, hesitation)
- Increased fuel consumption or exhaust smoke
- Hard starting or difficult cold start
- Possible fuel smell from exhaust or tank
What to check
- Read and record freeze-frame and live data with a good scan tool (misfire counts, fuel trim, injector pulse width)
- Check for stored related/secondary codes (P0204, P0304, fuel trim codes, low fuel pressure)
- Visually inspect the injector 4 connector and wiring for corrosion, damage, or pin push-out
- Backprobe injector connector while cranking/running to verify supply voltage and control pulsing
- Measure injector coil resistance (with connector disconnected) and compare to specification
- Use a noid light or oscilloscope to confirm injector drive pulse and waveform from PCM
Signal parameters
- Injector supply voltage: battery voltage (~11–14.5 V) present at constant feed terminal
- Injector control: pulsed ground from PCM; pulse width varies with engine load (typical pulses 0.5–6 ms; longer at higher load)
- Typical injector coil resistance: varies by design — commonly low-impedance injectors ~1–3 Ω (high-current) or high-impedance ~10–20 Ω; consult vehicle spec
- Pulse frequency: proportional to engine speed and injector strategy (individual cylinder pulses per combustion event)
- Expected current draw: depends on coil impedance and pulse width; abnormal open or short will change current signature
Diagnostic algorithm
- Connect a scan tool and record freeze-frame data and live PIDs (injector pulse width, fuel trims, misfire counters).
- Visually inspect connector and wiring for cylinder 4; repair obvious damage and corrosion. Ensure secure connector seating.
- With ignition OFF, disconnect injector harness and measure injector coil resistance. Compare to factory spec. Replace injector if out of spec or open/shorted.
- With harness connected, backprobe the feed terminal to confirm constant battery voltage present. Then backprobe the control terminal while cranking/running to confirm pulsed signal. Use a noid light or lab scope for waveform verification.
- If no pulse from PCM, check continuity between PCM and injector connector and inspect PCM ground and power feeds. Repair wiring as needed.
- Swap injectors between cylinder 4 and another cylinder. If the DTC/misfire follows the injector, replace the injector. If it stays on cylinder 4, focus on wiring/PCM driver.
- Check fuel rail pressure and fuel delivery. Low rail pressure can cause poor injector operation; correct fuel supply faults.
- If waveform shows abnormal shape (slow rise, clipped, excessive resistance), suspect wiring/connector or PCM driver. Consider current draw testing or component-level bench test.
- After repairs, clear codes, perform a test drive and re-scan to confirm the fault is resolved. If intermittent, instrument vehicle during conditions when the fault occurs (heat soak, vibration).
Likely causes
- Corroded/loose connector or wiring fault to injector 4
- Failed injector coil (open or high resistance)
- Injector control driver fault in PCM
- Clogged injector or internal mechanical failure
Fault status
Status
Fuel injector malfunction detected on cylinder 4. ECM has identified abnormal electrical or operational behavior of injector 4 (open, short, no pulse, or incorrect flow). Inspection of injector, connector, wiring and control circuit required.
Repair difficulty: Medium
Diagnostic time: 1.0-3.5 hours
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