Code
P1218
PORSCHE
P — Powertrain
Fuel injector, cylinder 6
Views:
UK: 4
EN: 6
RU: 4
AI status
Completed
Completed
100%
Causes
- Open or short in the injector wiring harness or connector for cylinder 6
- Corroded, loose or damaged injector connector or pin
- Failed fuel injector (stuck open, stuck closed or electrically open/shorted)
- Faulty ECM/PCM injector driver for cylinder 6
- Low or intermittent fuel rail pressure or fuel delivery problem
- Clogged or contaminated injector
Symptoms
- MIL/Check Engine lamp illuminated
- Misfire or rough running attributable to cylinder 6
- Rough idle and vibration
- Loss of power or hesitation during acceleration
- Reduced fuel economy and increased emissions
- Possible hard starting or stumble
What to check
- Read freeze frame and related codes with a capable scan tool; note misfire counts and long/short term fuel trims
- Visually inspect injector connector, pins and wiring for damage, corrosion or water ingress
- Backprobe injector connector: verify constant battery feed (KOEO) and switching ground/pulse from ECU while cranking/running
- Measure injector resistance with ohmmeter and compare to factory spec
- Use a noid light or oscilloscope to verify injector pulse pattern and pulse width under various conditions
- Perform a wiggle test on wiring while monitoring injector signal and engine behavior
Signal parameters
- Injector electrical resistance: refer to Porsche factory specification (typical low-impedance direct injectors can be ~1–16 Ω; verify exact value before replacement)
- Supply voltage at injector pin: approximately battery voltage (≈11–14 V) with key ON (KOEO)
- Injector control: switching ground/pulse from ECU; pulse width varies with load/engine speed (common pulse widths ≈1–6 ms depending on conditions)
- Pulse frequency correlates with engine RPM; waveform should be clean without excessive noise or missing pulses
- No continuous short to ground or open circuit on the driver line when engine is cranking/running
Diagnostic algorithm
- Connect scan tool, record current DTCs, freeze frame and live data (injector pulse, misfire counters, fuel trims).
- Clear codes and re-run to see if P1218 returns and under what conditions (hot/cold, idle/load).
- Visually inspect harness and connector at injector 6; repair obvious damage or corrosion.
- Measure injector coil resistance at the connector; compare with factory spec. If open or out of tolerance, replace injector.
- Backprobe connector with engine cranking/running: verify battery feed on one pin and ECU switching/pulse on the other. If no supply, trace fuse/relay/wiring. If no pulse, test ECU driver circuit.
- Use a noid light or oscilloscope on the driver pin to confirm pulse waveform and duty cycle. Look for missing pulses, irregular waveform or driver shorting.
- Swap injector 6 with another cylinder’s injector (if identical) and retest: if code follows injector, replace injector; if it stays on cylinder 6, suspect wiring or ECU.
- Check fuel rail pressure and volume to rule out low fuel pressure causing abnormal injector operation.
- If electrical supply and injector appear correct but performance issue remains, perform cylinder compression/leakdown and ignition checks to rule out mechanical causes.
- If wiring and injector check good, consider ECU driver failure and confirm with manufacturer procedures before replacing ECU.
Likely causes
- Poor electrical connection at the cylinder 6 injector (corrosion, broken pin, bent terminal)
- Failed or internally shorted injector on cylinder 6
- Damaged wiring harness (chafing, connector damage) to injector 6
- Faulty injector driver circuit in the ECU
Fault status
Status
Fuel injector circuit/operation fault detected for cylinder 6. Possible open/short, poor connection, failed injector, fuel delivery or ECU driver issue.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email