P0105
Manifold Absolute Pressure/Barometric Pressure Circuit MalfunctionP0105 is a generic OBD-II powertrain diagnostic trouble code: Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction. It is logged by the engine control unit when the air/maf monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0105 means
P0105 is a generic OBD-II code indicating a Manifold Absolute Pressure (MAP) or Barometric Pressure (BARO) sensor circuit malfunction. The MAP sensor provides the ECM with a real-time measurement of intake manifold vacuum or boost pressure, which is essential for calculating engine load, setting fuel injection quantity, and adjusting ignition timing. A P0105 malfunction code means the ECM has detected that the MAP circuit signal is entirely absent, implausible, or fails to correlate with data from other sensors such as the throttle position sensor — the signal is not simply out of its normal operating band (that would trigger P0106–P0108) but is fundamentally broken or stuck.
The MAP sensor is a three-wire device receiving a 5 V reference, a signal wire, and a ground. It may be mounted directly on the intake manifold or connected via a vacuum hose. Common failure points include cracked or dislodged vacuum hoses, corroded sensor connectors, open or shorted wiring, and the sensor itself losing its pressure-to-voltage transduction capability. Vehicles that use a combined MAP/BARO sensor may set P0105 on either the manifold or barometric measurement path.
Driveability impact ranges from moderate to severe: the ECM may enter open-loop fuel control using throttle position as a substitute, resulting in rough idle, poor acceleration, increased fuel consumption, hard starting, and in severe cases stalling or a no-start condition. The MIL will illuminate immediately on most platforms.
Common causes
Most-frequently reported root causes when P0105 is logged.
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1
Cracked, collapsed, kinked, or dislodged vacuum hose connecting the MAP sensor to the intake manifold.
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2
Corroded, damaged, or pushed-out pins in the MAP sensor electrical connector.
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3
Open or short circuit in the MAP sensor signal wire, 5 V reference wire, or ground wire.
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4
Failed MAP sensor with a dead pressure transducer outputting a constant or absent signal.
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5
Vacuum leak at the intake manifold gasket or throttle body causing implausible manifold pressure relative to throttle position.
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6
Loss of the 5 V reference supply to the MAP sensor (may affect other sensors sharing the same reference).
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7
PCM failure — internal reference voltage driver or signal-conditioning circuit fault (rare, diagnose last).
Symptoms drivers notice
How to diagnose P0105
A typical diagnostic flow when this code is present.
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1
Retrieve all codes and freeze-frame data with a scan tool; note whether any related sensor codes (TPS, MAF) are also present, which may indicate a shared 5 V reference problem.
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2
Inspect all vacuum hoses connected to the MAP sensor for cracks, blockages, or loose fittings; replace any that are soft, brittle, or disconnected.
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3
Inspect the MAP sensor connector and wiring harness for corrosion, damaged pins, or chafing against hot or moving components.
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4
With ignition on (engine off), measure the 5 V reference and ground at the MAP sensor connector; both must be present and within specification before suspecting the sensor or signal circuit.
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5
Monitor MAP sensor voltage live on the scan tool: at ignition-on/engine-off it should read approximately 4.5–5 V (barometric); at idle it should drop to roughly 1–2 V; under WOT it should rise toward 4.5 V — a stuck or absent reading confirms sensor or wiring fault.
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6
Apply a hand vacuum pump directly to the MAP sensor port (bypassing the hose); if voltage now transitions correctly, the fault is in the vacuum hose or manifold port.
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7
Replace confirmed faulty MAP sensor or repair wiring, clear codes, and verify normal MAP readings across idle, cruise, and wide-open-throttle during a test drive.
Related powertrain codes
- P0068 — MAP/MAF - Throttle Position Correlation
- P006A — MAP - Mass or Volume Air Flow Correlation Bank 1
- P00B8 — MAP - Mass or Volume Air Flow Correlation Bank 2
- P00BC — Mass or Volume Air Flow A Circuit Range/Performance - Air Flow Too Low
- P00BD — Mass or Volume Air Flow A Circuit Range/Performance - Air Flow Too High
- P00BE — Mass or Volume Air Flow B Circuit Range/Performance - Air Flow Too Low
Frequently asked questions
How is P0105 different from P0106, P0107, or P0108?
P0105 indicates a fundamental circuit malfunction — the signal is absent, stuck, or entirely implausible relative to other sensors. P0106 is a range/performance fault (signal is present but doesn't match expected values during normal operation). P0107 means the signal voltage is below the minimum threshold. P0108 means the signal voltage is above the maximum threshold. Think of P0105 as 'the circuit is broken,' while P0106–P0108 describe out-of-range but present signals.
Can a vacuum leak cause P0105?
Yes. A large vacuum leak — such as a torn intake boot, cracked manifold gasket, or disconnected hose — causes manifold pressure to be higher than the ECM expects given the throttle position and engine speed. If the discrepancy is severe enough to fall outside the plausibility window, the ECM may log P0105 rather than P0106.
Is it safe to drive with P0105 active?
Only for a short distance if necessary. Without a valid MAP signal the ECM switches to open-loop control using the throttle position sensor as a substitute, which leads to incorrect fuelling, potential misfires, and elevated catalyst temperatures. Prolonged driving risks catalytic converter damage and poor performance. Repair should be prioritised.
Could a faulty throttle position sensor cause P0105?
Indirectly. The ECM uses TPS data to validate MAP readings — if manifold pressure doesn't rise appropriately when the throttle opens, a plausibility conflict arises. A faulty TPS can therefore cause the ECM to flag the MAP circuit as implausible. Always check for TPS codes stored alongside P0105 and address them together.
Disabling P0105 in software
RaceTune can permanently disable P0105 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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