P1101 On GM and GM-era Saab engines, the airflow worked out from throttle position doesn't match the airflow measured by the MAF and MAP sensors

Intake air flow system performance (GM)

P1101 in short

On GM vehicles, P1101 means the airflow the engine computer expects from throttle position doesn't match what the MAF and MAP sensors report. The usual cause is air getting in after the sensor: a loose duct clamp, a cracked PCV part or a damaged turbo intercooler seal. Some engines show reduced power. Have it inspected soon.

GM engines cross-check three ways of judging how much air is coming in: the mass airflow (MAF) sensor, the manifold pressure (MAP) sensor, and a prediction from throttle position and engine speed. Saab service information for a GM V6 says P1101 sets when actual airflow is greater than the calculated figure.

That nearly always points to air the MAF didn't measure, entering through a loose clamp, split duct, leaking PCV or crankcase part or, on turbo engines, a leaking charge-air cooler connection. A sensor reading low, or mechanical engine faults, can also set it.

GM's bulletins match this. On Cruze, Sonic, Trax and Encore models it shows up with crankcase oil leaks and whistling at start-up, which suggest a failed PCV or valve cover part. GM also points to a missing charge-air cooler O-ring on many turbo models, which can bring a Reduced Engine Power message, and to the wrong air cleaner housing on Encore and Trax.

Pick your make

P1101 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Air leak after the MAF sensor (loose clamp, split duct)

    Common general cause
    Why it ranks here
    Unmetered air makes actual airflow exceed calculated airflow, the condition that sets the code; GM's Verano bulletin tightens duct clamps.
    What would change this
    Likelier if a hiss or loose clamp is found, or P0171 is stored too.
    How to test the vacuum hoses and intake leaks

  2. Crankcase ventilation (PCV) or valve cover fault

    Supported by vehicle data
    Why it ranks here
    GM ties P1101 to crankshaft seal oil leaks and a whistle at start-up on several small turbo engines, which point at crankcase pressure.
    What would change this
    Likelier with an oil leak or a whistle from the engine at start-up on those models.
    How to test the crankcase ventilation (pcv) valve

  3. Damaged or missing charge-air cooler coupler O-ring (turbo engines)

    Supported by vehicle data
    Why it ranks here
    GM's turbo bulletin points to this seal when P1101 comes with Reduced Engine Power.
    What would change this
    Likelier on turbo engines after intercooler or pipe work.

  4. MAF or MAP sensor reading wrong

    Possible — needs testing
    Why it ranks here
    Saab's diagnostic aids compare MAF and MAP readings; a sensor reading low makes calculated airflow too small.
    What would change this
    Likelier if live data shows the sensor out of line with no leak found.
    How to test the mass airflow (maf) sensor

  5. Wrong air cleaner housing (Encore and Trax)

    Supported by vehicle data
    Why it ranks here
    GM replaces air cleaner housings without the correct content for the engine on 2013-2019 Encore and Trax.
    What would change this
    Only relevant on those models.

  6. Camshaft actuators swapped after engine repair

    Supported by vehicle data
    Why it ranks here
    GM warns P1101 can follow engine work where the cam actuators went back on the wrong camshafts.
    What would change this
    Only likely right after engine repair.

  7. Engine computer calibration (older Cadillacs)

    Supported by vehicle data
    Why it ranks here
    GM updated the engine calibration on 2005-2006 SRX, STS and XLR models that set P1101 on cold starts with no performance concern.
    What would change this
    Only relevant on those models when the car runs normally.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read codes and freeze-frame data; note any lean codes, recent engine or turbo work, and whether the dash showed Reduced Engine Power

    Low riskTool: OBD-II scan tool

  2. With the engine off, check every clamp and duct between the air filter and the throttle, the PCV hoses, and for oil leaks or a whistle at start-up

    Low riskTool: Flashlight, screwdriver

  3. Compare MAF and MAP readings with expected values and run a smoke test of the intake

    Best left to a shopTool: Scan tool, smoke machine

    Warning:Smoke testing pressurises the intake; use proper equipment and follow the maker's procedure.

Symptoms

  • Check engine light
  • Reduced Engine Power message on some turbo engines
  • Whistle or hiss at start-up
  • Rough idle or hesitation

Compare with: Rough idle with the check engine light on

How to fix

  1. With the engine off, check that the air filter lid is latched and the intake duct clamps between filter and engine are tight.

  2. Ask a GM dealer whether a bulletin covers your VIN; several published fixes exist for P1101.

Parts and cost context

  • Mass airflow (MAF) sensor:Rule out intake and crankcase leaks before replacing the MAF; GM's published fixes are mostly seals, clamps and ventilation parts. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2011–2019 · Cruze

    Supported by vehicle data

    GM has a repair for P1101 and ties it to crankshaft oil leaks on 2016-2019 models. Whether the bulletins are still current is not verified.

  • 2013–2019 · Trax

    Supported by vehicle data

    Air cleaner housing check for P0171/P1101. Whether the bulletin is still current is not verified.

  • 2013–2022 · Malibu

    Supported by vehicle data

    Charge-air cooler O-ring and crankshaft oil leak bulletins mention P1101. Whether the bulletins are still current is not verified.

  • PI0907CStatus unverified

    Check engine light with P1101 (Cruze, Sonic, Trax, Encore)

    2011–2017cruze, sonic, trax · issued · NHTSA 10135296

    Repair information for the check engine light with P1101. Also Buick Encore.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 20-NA-047Status unverified

    Front or rear crankshaft oil leak with MIL and P1101

    2016–2022cruze, malibu, equinox, trax, volt · issued · NHTSA 10230607

    Front or rear crankshaft oil leak with MIL and P1101. Also Buick Encore and GMC Terrain.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Buick

  • 2013–2022 · Encore

    Supported by vehicle data

    Several GM bulletins: air cleaner housing, whistle at start-up and oil leaks with P1101. Whether the bulletins are still current is not verified.

  • 2013–2019 · Regal

    Supported by vehicle data

    Reduced Engine Power with P1101 from a damaged charge-air cooler O-ring. Whether the bulletin is still current is not verified.

  • 2013 · Verano

    Supported by vehicle data

    Loose air duct clamps can set P1101 with P0171 or P0101. Whether the bulletin is still current is not verified.

  • 18-NA-333Status unverified

    MIL, whistle noise at startup and P1101 (Encore)

    2018–2019encore · issued · NHTSA 10163889

    MIL on, whistle noise at start-up and P1101.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5402EStatus unverified

    P015B or Reduced Engine Power with P1101: check charge air cooler coupler O-ring

    2013–2019regal, envision, verano · issued · NHTSA 10167456

    P015B, or a Reduced Engine Power message with P1101: look for a missing or damaged charge-air cooler coupler O-ring. Also Chevrolet, Cadillac and GMC turbo models.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5240FStatus unverified

    P0171 and/or P1101: inspect air cleaner housing (Encore, Trax)

    2013–2019encore · issued · NHTSA 10163679

    MIL with P0171 and/or P1101: inspect the air cleaner housing and replace it if it lacks the correct content. Also Chevrolet Trax.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PI0931Status unverified

    SES light with P0171, P1101 and/or P0101: inspect and tighten air duct clamps (Verano)

    2013verano · issued · NHTSA 10134661

    Check engine light with P0171, P1101 and/or P0101: inspect and tighten the air duct clamps.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Cadillac

  • 2020–2026 · CT4

    Supported by vehicle data

    P1101 after engine work if cam actuators were swapped. Whether the bulletin is still current is not verified.

  • 2005–2006 · STS

    Supported by vehicle data

    Cold-start check engine light with P1101 and no performance concern; GM updated the engine calibration. Whether the bulletin is still current is not verified.

  • PIP6115Status unverified

    P1101/P0172 or stall off idle after cam actuator removal: check actuators on correct camshafts

    2020–2026ct4 · issued · NHTSA 11032955

    After engine repair removing the cam actuators, P1101/P0172 or stalling off idle: verify the actuators are on the correct camshafts. Also Chevrolet Colorado and Silverado 1500.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP-4542Status unverified

    SES light on cold start with P1101 and no performance concern: updated ECM calibration

    2005–2006sts, srx, xlr · issued · NHTSA 10032870

    Check engine light on cold start with P1101 and no performance concern; updated ECM calibration.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0171Engine computer has reached its limit adding fuel on bank 1: the mixture is lean

    Shares causes Supported by vehicle data

    Unmetered air also leans the mixture; GM's Encore and Trax bulletin lists P0171 with P1101.

  • P0101Airflow sensor reading doesn't match what the engine computer expects for the throttle opening

    Shares causes Supported by vehicle data

    GM's Verano bulletin lists P0101, a MAF performance code, with P1101 from loose duct clamps.

  • P0172Engine computer has reached its limit removing fuel on bank 1: the mixture is rich

    Shares causes Supported by vehicle data

    GM's bulletin covers P1101/P0172 or stalling off idle after cam actuator removal, when the actuators end up on the wrong camshafts.

All Air metering (MAF, MAP and intake air temperature) codes

P1101 questions

Is P1101 a bad MAF sensor?

Sometimes, but on GM engines it most often means air is getting in after the MAF: a loose clamp, crankcase ventilation fault or a leaking turbo seal. Check for leaks first.

Sources and review

  1. PIP5402E: P015B or Reduced Engine Power with P1101: check charge air cooler coupler O-ring — General Motors / NHTSA ,
  2. 2023 Integra Owner's Manual: Indicator, Coming On/Blinking — American Honda Motor Co.
  3. DTC P0068 or P1101 (2011 Saab 9-4X, V6 engine management) — Saab Automobile / General Motors service information (Saab WIS)
  4. PI0931: SES light with P0171, P1101 and/or P0101: inspect and tighten air duct clamps (Verano) — General Motors / NHTSA ,
  5. 20-NA-047: Front or rear crankshaft oil leak with MIL and P1101 — General Motors / NHTSA ,
  6. 18-NA-333: MIL, whistle noise at startup and P1101 (Encore) — General Motors / NHTSA ,
  7. PIP5240F: P0171 and/or P1101: inspect air cleaner housing (Encore, Trax) — General Motors / NHTSA ,
  8. PIP6115: P1101/P0172 or stall off idle after cam actuator removal: check actuators on correct camshafts — General Motors / NHTSA ,
  9. PIP-4542: SES light on cold start with P1101 and no performance concern: updated ECM calibration — General Motors / NHTSA ,
  10. PI0907C: Check engine light with P1101 (Cruze, Sonic, Trax, Encore) — General Motors / NHTSA ,
Last reviewed
Written by
Saurabh K.
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