Code
P1122
DAEWOO
P — Powertrain
BOOSTER PRESSURE SNSR - HIGH
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UK: 1
EN: 5
RU: 5
AI status
Completed
Completed
100%
Causes
- Faulty boost/booster pressure sensor (MAP/boost sensor)
- Short circuit in signal wire to battery voltage (Vbatt)
- Poor sensor ground or damaged wiring/harness connector
- Actual overboost condition (wastegate/turbo control fault)
- Blocked or collapsed boost/vacuum hose or intake leak causing incorrect readings
- Faulty boost control solenoid or wastegate actuator
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine performance or limp-home mode
- Unstable idle or surging when under boost
- Poor fuel economy and hesitation/torque loss
- Possible visible boost overpressure (whine/abnormal noise) or smoke if severe
What to check
- Retrieve freeze frame and live data with a scan tool; note boost/sensor voltage vs. RPM/load
- Visually inspect sensor, connector, and wiring for damage, corrosion, or pin push-out
- Backprobe sensor signal, reference (5V) and ground circuits with multimeter/oscilloscope
- Compare sensor signal to a trusted reference: direct manifold pressure reading with a mechanical gauge
- Pressure-test boost system (including intercooler and hoses) for leaks or blockages
- Verify operation of boost control solenoid and wastegate actuator
Signal parameters
- Sensor supply/reference: approximately 5 V (engine ECU regulated)
- Sensor ground: close to 0 V; low resistance to chassis ground
- Signal output: varies with absolute manifold/boost pressure; typically 0.1–4.9 V range depending on sensor type
- At atmospheric pressure the signal is usually in the mid-range for the specific sensor (consult vehicle spec)
- A high signal compared to expected for a given engine speed/load triggers the code
Diagnostic algorithm
- Read and record freeze-frame data and all stored DTCs. Note engine conditions when fault occurred.
- With a scan tool, monitor live MAP/boost value and sensor voltage while revving engine. Confirm sensor shows abnormally high values.
- Visually inspect connector and wiring at the booster pressure sensor for corrosion, pin damage, or evidence of wiring chafe/repair.
- Backprobe sensor pins: verify reference voltage (~5 V) present with ignition on, verify good ground continuity, and measure signal voltage. If signal is near battery voltage with ignition on or during run, suspect short to Vbatt or failed sensor.
- If suspecting electrical fault, disconnect sensor and check signal line voltage at harness connector. If elevated with sensor disconnected, trace wiring for short to 12 V (splice, relay, aftermarket accessory).
- If electrical checks pass, connect a mechanical boost gauge to intake and compare actual manifold pressure to sensor reading. If mechanical gauge shows normal pressure but sensor reads high, replace sensor.
- If mechanical gauge shows overboost, inspect turbocharger wastegate, boost control solenoid, vacuum lines and actuator; test solenoid operation and replace or repair as needed.
- After repairs, clear codes and road-test while monitoring live data to confirm correct sensor behavior and no recurrence of code.
- If wiring and sensor are good but code persists, consult manufacturer service information for connector pinouts, wiring diagrams, and ECM troubleshooting; consider ECM test/reprogram as last resort.
Likely causes
- Damaged sensor or connector wiring shorted to 12 V
- Wiring short to battery voltage at sensor harness
- Sensor ground open or high resistance
- Mechanical overboost (stuck wastegate or failed boost control valve)
Fault status
Status
Booster pressure sensor signal is higher than expected. Check sensor, wiring for short to battery, grounds, and inspect boost control and turbo system for overpressure.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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