P0105 – Manifold absolute pressure/barometric pressure sensor circuit short to battery or open

Last updated: April 8, 2026

P0105 is a powertrain, ISO/SAE controlled diagnostic trouble code that sets when the engine control module detects the manifold absolute pressure/barometric pressure sensor circuit is either open or shorted to battery voltage. Because this is a circuit/open or short type fault, the priority is verifying the electrical integrity of the sensor’s power, ground, and signal circuits rather than assuming the sensor itself is inaccurate. When the pressure signal circuit is forced high by battery voltage or lost due to an open, the controller can no longer rely on that input and may substitute a default value. That can affect fueling, ignition decisions, and overall drivability. A structured diagnosis—scan data review, careful visual inspection, then targeted electrical checks—helps you pinpoint whether the fault is wiring, connector, or sensor related.

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P0105 Quick Answer

P0105 means the manifold absolute pressure/barometric pressure sensor circuit is open or shorted to battery. Start by reviewing freeze-frame and live scan data for a stuck, missing, or implausible pressure signal, then inspect the sensor connector and harness for damage. Next, confirm the reference supply, ground, and signal circuit behavior with a meter and simple load testing to identify an open or a short to battery before replacing any parts.

What Does P0105 Mean?

P0105 indicates the control module has detected an electrical failure in the manifold absolute pressure/barometric pressure sensor circuit—specifically an open circuit or a short to battery. In plain terms, the module is seeing a pressure-sensor circuit state that cannot be trusted as a valid sensor signal because the circuit is either not electrically connected as expected (open) or is being driven toward battery voltage (short to battery).

This code describes a circuit integrity problem, not a guaranteed sensor accuracy problem. An open in a wire, a poor terminal connection, corrosion, or a short that contacts battery voltage can all create the electrical conditions that meet the code’s definition. Your diagnostics should therefore focus on proving whether the circuit is intact and correctly powered/grounded and whether the signal wire is free of unwanted battery voltage.

Theory of Operation

The manifold absolute pressure/barometric pressure sensor is an electrical pressure sensor that provides the control module with a signal representing pressure. The module uses that pressure information as a key input for engine management calculations, and the circuit must have stable electrical power/ground and a valid signal path for the reading to be usable. When the circuit is healthy, the signal changes in a predictable manner as operating conditions change, and the module can interpret the sensor output as a real pressure value.

P0105 sets when the module detects an electrical fault pattern consistent with either an open circuit or a short to battery on the sensor circuit. An open can prevent the module from receiving a meaningful signal, while a short to battery can force the signal toward an abnormally high electrical level. Either condition can cause the signal to be missing, stuck, or otherwise electrically invalid. Because the failure mode is circuit-related, the code tends to set when wiring, terminals, or electrical supply/return paths are compromised, even if the sensor element itself is not damaged.

Symptoms

• The check engine light illuminates and may return soon after clearing if the circuit fault is still present.
• The engine may have reduced power or delayed response because the control module cannot rely on the pressure input.
• The engine may crank longer than normal or start inconsistently if the pressure signal circuit is unavailable.
• The idle may be rough or unstable when the module substitutes a default value for the missing/invalid signal.
• The vehicle may hesitate or surge during changes in throttle due to incorrect engine load calculation.
• Fuel economy may decrease because the control module’s calculations are based on a substituted or incorrect pressure input.
• The engine may stall at low speed or when coming to a stop if the substituted strategy does not match actual conditions.

Common Causes

• An open in the sensor signal circuit can prevent the control module from receiving a usable pressure signal, which matches the “open” portion of the code definition.
• A short to battery on the signal circuit can drive the signal toward battery voltage, creating an electrical state the module recognizes as “short to battery.”
• A poor connection at the sensor connector (corrosion, loose pin fit, or a backed-out terminal) can create intermittent opens that repeatedly break the circuit and set the code.
• Damaged wiring insulation can allow the harness to contact a battery voltage source, producing a short to battery that forces an invalid signal level.
• An open or high-resistance in the sensor’s supply or return path can prevent proper circuit operation, leading the module to interpret the circuit as open/invalid.
• Water intrusion at connectors can create corrosion and unintended current paths, resulting in unstable readings that present as an open or short-to-battery condition.
• A connector issue at the control module side can interrupt the signal path or introduce an unwanted high-voltage condition, causing the module to detect an open or short.
• An internal fault in the sensor can, in some cases, fail in a way that effectively opens the circuit or biases the signal toward a battery-level condition, meeting the code criteria.

Diagnosis Steps

Tools you need: a scan tool capable of reading codes, freeze-frame, and live data; a DVOM (digital volt/ohm meter); back-probing pins or breakout leads; basic hand tools for connector access; and appropriate wiring information for the manifold absolute pressure/barometric pressure sensor circuit.

1. Connect the scan tool and confirm P0105 is present as stored or pending. Record freeze-frame data, including ignition status, engine speed, and any available pressure signal parameter shown at the time of the fault. Then check if the code resets immediately after clearing, which can indicate a hard open or hard short to battery.
2. Review live data related to the manifold absolute pressure/barometric pressure sensor circuit while key-on and, if possible, while the engine runs. Look for a signal that is stuck, missing, or not behaving consistently with basic operating changes. If the signal appears pinned high or does not respond at all, prioritize checks for a short to battery or an open.
3. Perform a focused visual inspection of the sensor, connector, and harness routing. Look for broken locks, bent pins, corrosion, oil saturation, or harness damage where the loom bends or rubs against brackets. Because this is a circuit/open or short code, any sign of chafing or pin tension issues should be treated as a primary lead.
4. With the key off, disconnect the sensor connector and inspect both sides closely. Verify terminals are not spread, pushed back, or corroded, and confirm the connector seals are intact. Repair terminal issues first because intermittent opens at the connector can mimic a wiring break and repeatedly set P0105.
5. Key on and use the DVOM to verify the circuit’s electrical supply and return at the sensor connector as specified by the wiring information. Do not rely only on continuity; measure voltage and perform a simple loaded check where appropriate to ensure the circuit can carry current, not just show voltage with no load. If the supply/return is unstable, correct that before diagnosing the signal wire.
6. Check the signal circuit for a short to battery with the sensor disconnected. With key on, measure voltage on the signal terminal relative to ground and compare it to battery voltage; a reading near battery voltage strongly suggests a short to battery on the signal circuit. If you find battery-level voltage, isolate the harness section by section to locate the contact point or pinched area.
7. Check the signal circuit for an open condition by verifying the circuit path between the sensor connector and the control module connector per the wiring information. Perform the test with connectors safely disconnected and confirm the circuit is not open and not high resistance. If continuity is intermittent, manipulate the harness gently to locate a break inside the insulation.
8. Reconnect the sensor and back-probe the signal circuit while monitoring live data, then perform a wiggle test. Move the harness near the connector and along likely rub points while watching for sudden dropouts or spikes consistent with an intermittent open or an intermittent short to battery. If the reading changes sharply with harness movement, focus repairs on that exact area.
9. If wiring and connector integrity are proven and no short to battery or open is found, verify the sensor’s circuit behavior under the same conditions that set the code. If P0105 still resets with known-good power/ground and a verified signal path, the sensor may be failing electrically in an open/short mode, or the module-side input may have a connector/pin issue not yet identified. Confirm findings with repeatable testing before replacing components.

Professional tip: For a circuit/open or short-to-battery code, prioritize proving the fault electrically rather than chasing drivability symptoms. If you can demonstrate battery voltage on the signal wire with the sensor unplugged, or a repeatable loss of continuity during a wiggle test, you have evidence of the exact failure mode described by P0105.

Possible Fixes

• Repair damaged wiring that is open in the manifold absolute pressure/barometric pressure sensor circuit, then secure the harness to prevent repeat stress.
• Locate and repair the short to battery on the sensor signal circuit by correcting chafed insulation, pinched harness sections, or incorrect routing.
• Clean corrosion and restore proper terminal fit at the sensor connector to eliminate intermittent opens.
• Repair connector or terminal issues at the control module connection that interrupt the circuit or introduce an unwanted high-voltage condition.
• Replace the manifold absolute pressure/barometric pressure sensor if testing proves the circuit is intact and the sensor is electrically failing open or biasing the circuit toward battery voltage.
• Correct water intrusion sources and reseal connectors to prevent recurring corrosion-related open/short conditions.

Can I Still Drive With P0105?

Driving with P0105 may be possible in some cases, but it carries real drivability risk because the code indicates an open circuit or a short to battery in the manifold absolute pressure/barometric pressure sensor circuit. If the control module cannot trust that circuit, it may substitute a default value that can cause hesitation, stalling at low speed, or reduced power during acceleration. If you experience stalling, severe hesitation, or unpredictable response, avoid driving and diagnose the circuit promptly. Even if it seems to drive acceptably, continued operation can increase fuel consumption and may worsen drivability if the circuit fault becomes intermittent under vibration or heat.

How Serious Is This Code?

P0105 should be treated as a fix-soon electrical fault because it indicates the manifold absolute pressure/barometric pressure sensor circuit is open or shorted to battery. Electrical circuit faults can change suddenly from intermittent to constant, and a short-to-battery condition can create repeated fault resets and unstable sensor input. While it may not always cause immediate no-start, it can create reduced power, stalls, and inconsistent operation that can become a safety concern in traffic. Addressing the circuit problem early also reduces the chance of unnecessary parts replacement and repeated drivability complaints.

Common Misdiagnoses

The most common misdiagnosis for P0105 is replacing the manifold absolute pressure/barometric pressure sensor without first proving an open circuit or a short to battery in the wiring or connectors. Because the official meaning is explicitly “circuit short to battery or open,” treating it like a sensor performance issue leads to missed chafed wires, corroded terminals, or poor pin fit that will immediately trigger the code again. Another frequent error is checking only continuity with the circuit unpowered and declaring the wiring good, even though an intermittent open or a short to battery may only appear under vibration, heat, or when the harness is positioned a certain way.

Most Likely Fix

The most likely fix for P0105 is restoring circuit integrity at the manifold absolute pressure/barometric pressure sensor connector or harness, such as repairing an intermittent open caused by poor terminal fit or correcting wiring damage that creates a short to battery. Confirm the repair by clearing the code and verifying the fault does not reset during a controlled wiggle test and during normal operation while monitoring the pressure signal on the scan tool. Replace the sensor only after you have proven the circuit is not open and not shorted to battery and that power/ground conditions are correct.

Repair Costs

Repair cost depends on whether the root cause is an external fluid leak, air in the system, an internal hydraulic component, or a sensor/plausibility issue. Confirm the root cause with a pressure and visual inspection before replacing hydraulic components.