P1108 — High input of the absolute pressure circuit of the collector

Diagnostic algorithm

1. Retrieve freeze frame and live data. Note MAP voltage and kPa and conditions when code set (engine load, rpm, boost).
2. With key ON engine OFF, measure reference voltage at MAP sensor connector. It should be ~5V. If missing or low, trace to ECU harness/connector.
3. Measure sensor ground continuity to chassis/ECU. Repair any poor grounds.
4. Backprobe the signal wire with a multimeter or oscilloscope. Check for voltage exceeding expected range or stuck at battery voltage.
5. Inspect wiring harness and connector for chafing, pin corrosion, melted insulation, or signs of short to power. Repair wiring as required.
6. If wiring appears good, remove sensor and bench test or swap with a known good MAP sensor. Confirm proper voltage vs. applied vacuum/pressure per specification.
7. If signal is correct with known-good sensor, suspect ECU driver circuit—verify ECU connector and continuity, consider ECU diagnosis/repair.
8. If overpressure suspected (turbocharged vehicles), inspect boost control components (wastegate, boost control solenoid, boost hoses) and measure actual intake boost with a gauge to confirm mechanical overboost.
9. After repairs, clear codes, perform a road test under same conditions, and re-scan to confirm fault does not return.