Code
P1552
PORSCHE
P — Powertrain
Idle control valve closing coil
Views:
UK: 4
EN: 4
RU: 3
AI status
Completed
Completed
100%
Causes
- Open or shorted closing coil winding in the idle control valve
- Damaged, corroded, or loose connector or wiring (open, short to ground, short to battery)
- Poor ground or insufficient supply voltage to the valve
- Contaminated/sticking idle control valve or mechanical blockage
- Faulty ECU/driver output for the ICV circuit
- Intermittent connection due to vibration or broken wire
Symptoms
- Check Engine Light (MIL) illuminated with P1552 stored
- Rough or unstable idle, surging, or fluctuating idle RPM
- Engine stalls on idle or at low speed
- Poor driveability when engine load changes at idle
- May clear temporarily after multiple key cycles or reconnecting connector
What to check
- Retrieve freeze-frame and readiness data with a scanner, confirm P1552 and related codes
- Visual inspection of ICV, connector, and wiring for corrosion, bent pins, insulation damage, or oil contamination
- Check for vacuum leaks and throttle body contamination that may cause valve to stick
- Backprobe ICV connector while operating (with scanner commanding ICV) and observe voltage/signal
- Measure ICV coil resistance at the connector and compare to specification
- Perform wiggle test on wiring while monitoring live data or MIL for intermittent faults
Signal parameters
- Typical idle control valve closing coil DC resistance: approx. 5–50 ohms (manufacturer-specific — consult service data)
- Activation voltage: near battery voltage when commanded (approx. 11–14 V) or PWM duty from ECU
- Typical coil current draw: ~0.2–1.5 A depending on design
- No continuity (infinite resistance) indicates open coil; very low resistance (
Diagnostic algorithm
- Read and record DTC(s), freeze-frame and live data. Check for related idle or throttle codes (P0505–P0507).
- Perform a careful visual inspection of the ICV, connector, wiring harness, and grounds. Repair obvious damage.
- With ignition off, disconnect connector and measure coil resistance across the ICV closing coil terminals. Compare to service spec. If out of range, replace ICV.
- Check for short to battery or ground: measure resistance from each coil terminal to ground and to battery using multimeter (expect no direct short).
- With ignition ON (engine off) backprobe connector and command ICV using scanner while observing voltage waveform/duty. Verify ECU is commanding and voltage behavior corresponds to specification.
- If ECU commands but coil shows no activation and coil resistance is good, apply bench 12 V briefly to the coil (observe polarity and safety) to confirm mechanical operation — only if safe and per service manual.
- Inspect throttle body and ICV for carbon buildup; clean if contaminated and re-test.
- If wiring and valve test good but no operation, trace/repair wiring to ECU and check ECU driver output. Replace ECU only after confirming driver fault per manufacturer procedure.
- Clear DTCs and conduct test drive / idle verification to confirm repair.
Likely causes
- Wiring/connector corrosion or break at the idle control valve
- High resistance or open coil in the ICV
- ICV sticking or contaminated (mechanical cause)
- ECU output driver fault (less common)
Fault status
Status
Idle control valve closing coil circuit fault — open/high resistance/short or ECU driver malfunction detected.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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