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DTC codes / GM codes / P1106

P1106 · GMMAP Sensor Circuit Voltage Intermittent

P1106 on a GM vehicle means the powertrain control module (PCM) has seen the manifold absolute pressure (MAP) sensor signal voltage jump or drop intermittently rather than follow a smooth, predictable curve. The PCM compares the MAP signal against throttle position and engine speed, and when the voltage briefly falls outside the expected window it flags the circuit as intermittent.

SystemPowertrain
Code typeGM specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Often no symptoms besides the warning light, especially if the glitch is brief and the PCM can still use the signal.
  • An occasional stumble, hesitation, or rough idle that comes and goes, particularly on bumps or during wet weather.
  • Momentary loss of power or a surge while accelerating as the PCM reacts to a false MAP reading.
  • Poor fuel economy or black smoke from the tailpipe if the intermittent signal reads rich for long stretches.
  • A stored P1106 with no drivability complaint at all, found only during a scan for another reason.

Common causes, most likely first

  1. Chafed, cracked, or corroded wiring between the MAP sensor and the PCM, often at the connector or where the harness rubs.
  2. A failing MAP sensor that drops out internally when hot or vibrating.
  3. Loose or backed-out terminals in the MAP sensor connector or PCM connector.
  4. A poor ground or reference voltage supply shared with other sensors on the same circuit.
  5. Moisture or oil intrusion into the MAP sensor connector causing an intermittent short.
  6. A vacuum leak at the MAP sensor mounting or intake manifold that makes the signal erratic under certain conditions.
  7. Rarely, an internal PCM driver fault on the MAP signal circuit.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to see the engine conditions when the code set.
  2. Inspect the MAP sensor connector and harness for chafing, corrosion, or loose terminals, wiggling the harness while watching live MAP voltage on the scan tool.
  3. Back-probe the MAP sensor signal wire and compare scan-tool voltage to a multimeter reading to confirm the PCM is seeing the same glitch.
  4. Check the MAP sensor reference voltage and ground at the connector with a multimeter, looking for drops or intermittents while flexing the harness.
  5. Test the MAP sensor with a hand vacuum pump and watch for a smooth voltage change; replace it if the signal jumps or flatlines.
  6. If wiring and sensor check out, load-test the signal circuit and inspect the PCM connector for terminal tension or corrosion.
  7. Clear the code and road-test over bumps and through the full throttle range to confirm the repair before returning the vehicle.

Why a wiggle test beats parts swapping

  • A P1106 is frequently set by a harness rub near the intake or a corroded connector pin, not by a failed MAP sensor, so a wiggle test with a live-data graph finds more of these than replacement does.
  • The PCM can set this code from a single brief glitch during a cold start or a hard bump, which is why many vehicles show the light with no drivability complaint at all.
  • A vacuum leak at the MAP sensor O-ring or intake can mimic an intermittent sensor fault because the signal moves without a matching throttle change.
  • Technicians who replace the MAP sensor without checking reference voltage and ground often see the code return, since a shared 5-volt supply fault can affect other sensors too.
  • On some GM engines the MAP sensor shares its ground with the throttle position sensor, so a bad ground can set P1106 alongside throttle-related codes.

Can I keep driving with P1106?

You can usually drive short distances to a shop, but avoid hard acceleration and towing until the fault is repaired because an intermittent MAP signal can cause a lean or rich condition that stresses the engine and catalytic converter. If the engine stumbles badly or the light flashes, stop driving and have it towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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