P0107: Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
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What does the P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input mean?
DTC P0107 is defined as “Manifold Absolute Pressure/Barometric Pressure Circuit Low Input.” In plain terms, the engine computer has detected that the MAP sensor output voltage is below its normal operating range.
The MAP sensor monitors the intake manifold’s absolute pressure (engine vacuum). Under load (throttle open, higher RPM) manifold pressure rises; at idle, manifold vacuum is high and pressure low. The ECU uses this MAP data to gauge engine load and adjust air-fuel ratio, ignition timing and EGR operation.
A separate BARO sensor measures ambient atmospheric pressure. In practice, many modern vehicles integrate MAP and BARO in one unit or use the MAP sensor’s key-on reading as the barometric reference. The only difference is location – the MAP sensor is plumbed to the manifold, while a BARO is vented to outside air.
The ECM monitors the MAP/BARO signal as part of its engine load calculation. In speed-density fuel injection systems, the ECM combines the MAP voltage with inputs like engine speed (RPM) and throttle position (TPS) to estimate airflow and set fuel and ignition.
If MAP signal output is “stuck” near 0 V (well below what the ECM expects for any reasonable manifold pressure), the computer flags P0107. This is typically worse than a “range” issue (P0106); it means the signal is essentially missing or shorted to ground.
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When the P0107 Triggers?
The Engine Control Module (ECM) continuously monitors the Manifold Absolute Pressure (MAP) sensor signal to determine engine load and calculate the correct fuel injection and ignition timing. To ensure the MAP sensor is operating correctly, the ECM performs several plausibility checks by comparing the MAP signal against engine operating conditions such as throttle position, engine speed, and barometric pressure.
The MAP sensor typically receives a 5-volt reference signal and ground from the ECM and returns a voltage signal that changes according to intake manifold pressure.
Typical MAP Sensor Voltage Readings
| Engine Condition | Manifold Pressure | Typical MAP Voltage |
|---|---|---|
| Key On, Engine Off (KOEO) at Sea Level | ~101 kPa | ~4.0–4.8 V |
| Idle | ~20–40 kPa | ~0.8–1.5 V |
| Light Cruise | ~40–60 kPa | ~1.5–3.0 V |
| Wide Open Throttle (WOT) | ~95–100 kPa | ~4.5–5.0 V |
| P0107 Fault Threshold | < ~5 kPa | < ~0.2 V (below this triggers fault) |
Note: Actual values vary depending on vehicle manufacturer, altitude, engine design, and sensor calibration.
The fault threshold for P0107 is very low. For example, Ford’s OBD-II strategy sets P0107 if MAP output drops below 0.19 V. Mitsubishi’s rule is similar: MAP ≤5 kPa (≈1.5 inHg) for 2 seconds (about 0.2 V). In practice, the ECM looks for a steady near-zero MAP signal that doesn’t make sense given the engine operating state.
In summary, P0107 triggers when the MAP/BARO sensor output voltage stays abnormally low (typically <0.2–0.5 V) for more than a brief time.
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How To Fix P0107?
Diagnosing P0107 follows a systematic approach:
| Step | Action | What to Check |
|---|---|---|
| 1 | Clear codes & road test | Confirm P0107 returns. |
| 2 | Visually inspect intake system | Check for damaged, disconnected or collapsed vacuum lines and intake leaks. |
| 3 | Inspect MAP sensor and connector | Look for cracks, oil/debris, loose connector or corrosion. |
| 4 | Verify 5 V reference at sensor | With ignition on, backprobe the MAP’s 5V supply pin; should read ~4.5–5.1 V. |
| 5 | Verify ground at sensor | Check MAP sensor ground pin with ignition on; should read ~0 V. |
| 6 | Backprobe MAP signal (ign on, engine off) | With key on, engine off: MAP voltage should be high (~4–5 V). |
| 7 | Check MAP signal at idle (engine running) | At idle, MAP voltage should be low (~0.5–2 V for NA engines). |
| 8 | Use hand-held vacuum pump | Apply vacuum to MAP and watch voltage drop: e.g. at ~5 inHg it should be ~3–4 V, at 20 inHg ~1 V. Voltage should change smoothly. |
| 9 | Analyze results | If MAP output stays near 0 V or does not move with vacuum: suspect short/wiring fault or bad sensor. If MAP voltage changes appropriately: suspect external issue (e.g. leak) or intermittent fault. |
| 10 | Repair fault: | Replace MAP sensor if it fails bench test. Repair/replace wiring or connectors if open/short found. Fix any intake leaks found. |
| 11 | Clear codes & retest | Verify that P0107 does not return and engine runs normally. |
Diagnosing P0107 logical flowchart:
Read our free complete guide on Kindle and learn how to diagnose sensor-related issues with clarity and confidence.
STOP GUESSING. START DIAGNOSING. SAVE HUNDREDS ON REPAIRS.
Tired of expensive repair bills and mechanics who “parts-cannon” your car without finding the real issue? The “Check Engine” light shouldn’t be a mystery. This guide puts professional-level diagnostics in your hands.
Possible Root Causes of P0107
Some common root causes of the P0107 error code include:
1. Vacuum Leak (Intake or Hose Leak)
A vacuum leak (from a cracked hose, loose fitting, or intake manifold gasket leak) lets outside air into the manifold, causing the MAP reading to be lower (higher vacuum) than expected.
For example, a leak in the MAP hose or at the manifold boot means the sensor sees less pressure than the engine actually has. The ECU, comparing this aberrant low pressure to the expected value, will flag a fault.
Fix: Carefully inspect the intake system for vacuum leaks. Check all vacuum hoses, intake ducting, PCV lines, and intake manifold gaskets for cracks, loose connections, or damage. A professional smoke machine can be used to introduce non-toxic smoke into the intake system. Smoke escaping from hoses, gaskets, or fittings will help pinpoint the source of the leak. Once identified, repair or replace the faulty component and clear the trouble code.
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2. Faulty MAP Sensor
The MAP sensor itself may be defective (stuck diaphragm, internal short, or contamination). For example, the internal sensing element can wear out or be damaged by heat/oil. A faulty MAP often reports a fixed voltage (e.g. high or low) regardless of actual pressure.
Fix: Replace the MAP sensor with an OEM-quality unit. Many MAP sensors come with a pigtail harness; be sure to match the OE part number.
Recommended product: Bosch or Delphi MAP sensor
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3. Wiring/Connector Issue
Damaged wiring or connectors can cause intermittent or incorrect signals. Corrosion at the connector, a broken wire in the loom, or a short between the signal and 5V reference will all generate wrong voltage to the ECU.
Fix: Inspect the MAP sensor connector for bent pins, corrosion, or moisture. Wiggle the wiring harness while monitoring MAP voltage – spikes or drops indicate a wiring fault. Repair any chafed wires or replace the connector. Use dielectric grease on the connector to prevent corrosion.
Recommended product: A repair wire harness pigtail for your MAP sensor (if available), or general electrical repair kit (for splicing and insulating wires).
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4. Clogged/Dirty MAP Port
Carbon, oil, or debris in the MAP sensor’s vacuum port or hose can impede the pressure signal. For example, if the small hose fitting to the sensor is partially blocked, the ECU will read incorrect pressure.
Fix: Remove the MAP sensor and blow through its port and hose. Clean with a dedicated sensor or throttle-body cleaner (do not use harsh chemicals that leave residue). Ensure the port under the sensor is free of gasket material. If contamination has entered the sensor, replacement is safer.
Recommended product: Mass Airflow/MAP sensor cleaner (such as CRC or WD-40 LOD) to clean orifices without damaging the sensor.
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5. Faulty BARO Sensor (if separate)
Some engines have a separate barometric (BARO) pressure sensor. If the BARO sensor fails or its vent line is blocked, the ECU gets bad ambient pressure data. This usually only matters on cars where MAP and BARO are distinct.
Fix: If your vehicle has a separate BARO (often on the intake plenum or MAF housing), test it like a MAP sensor (see service manual). A bad BARO can often set P0106/P0107/P0108 as well, but in some systems it may trigger P0106. Replace the BARO sensor if it’s defective.
Recommended product: Genuine BARO sensor or intake-manifold pressure sensor (often the same part number as MAP on some models).
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6. Faulty ECU (Rare)
In very rare cases, the powertrain control module itself is at fault (bad analog input for MAP/BARO). This could happen if the ECU’s internal reference source or ADC channel is damaged.
Fix: Confirm all else is good before blaming the ECU. If wiring and sensors test fine, an ECU reflash or replacement may be needed. This is usually done at a dealership or professional shop.
Note: Always double-check wiring, grounds and sensors first – ECM failure is uncommon.
Common Diagnostic Mistakes
- Replacing MAP sensor prematurely: A very common error is to assume the sensor is bad without thorough testing. Often a vacuum leak or wiring issue is the real culprit. Always verify with electrical tests or a vacuum pump before swapping the MAP sensor.
- Using a Low-Impedance Meter: Always use a high-impedance (≥10 MΩ) voltmeter when probing sensor circuits. A low-Ω meter can load the circuit and give false readings.
- Misidentifying Vacuum Leaks: An intake vacuum leak typically causes a higher MAP reading (lean condition), not the low voltage of P0107. (A normal leak tends to set lean codes, not P0107.) Confusing P0107 for a general vacuum leak issue is a common error.
- Ignoring Freeze-Frame Clues: Forgetting to compare MAP voltage with throttle/RPM in the snapshot can lead to missing the “plausibility” aspect of the fault.
- Skipping Re-learning: After repairs, the ECM may need some drive cycles or a forced idle relearn to recalibrate fuel trims. Some forget to fully clear codes and relearn.
Related Codes
- P0105: MAP/BARO Circuit Malfunction: Indicates a reference voltage or circuit problem (open/short) in the MAP sensor circuit. Often P0105 must be resolved before addressing P0107.
- P0106: MAP/BARO Circuit Range/Performance Problem (sensor out of normal range)
- P0108: “MAP/BARO Circuit High” – The MAP voltage is too high (above expected) at engine off or wide throttle. Indicates a short to 5 V or stuck-high reading.
- P0171 / P0174: “System Too Lean (Bank 1/2)” – Lean fuel trim codes. A vacuum leak (a common P0107 cause) or failing MAP can cause these lean codes.
- P0300 (and P0301–P0308): “Random/Multiple Cylinder Misfire” – Erratic MAP signals or vacuum leaks can lead to misfires under load, setting P0300 series faults.
- P0110: “Intake Air Temperature Sensor” – While not directly a MAP code, it’s related in that it measures intake conditions. It’s worth checking IAT if the intake is contaminated.
| Code | Definition | What It Means |
|---|---|---|
| P0105 | MAP/BARO Circuit Malfunction | General electrical fault in the MAP/BARO circuit. ECM cannot trust the sensor signal. |
| P0106 | MAP/BARO Circuit Range/Performance Problem | Sensor signal exists but doesn’t match expected engine operating conditions. |
| P0107 | MAP/BARO Circuit Low Input | MAP voltage stuck too low (typically below ~0.5V). Often caused by a short to ground, faulty sensor, or wiring issue. |
| P0108 | MAP/BARO Circuit High Input | MAP voltage stuck too high (typically above ~4.5V). Often caused by a short to 5V, failed sensor, or disconnected vacuum source. |
| P0109 | MAP/BARO Circuit Intermittent | Signal drops in and out unexpectedly due to loose connections, damaged wiring, or intermittent sensor failure. |
What does the P0107 code mean?
P0107 means the PCM has detected the MAP sensor signal is too low – essentially the MAP/BARO circuit voltage is below the allowed range. In other words, the MAP sensor output is stuck near 0 V when the ECM expects a higher voltage.
What causes the P0107 code?
The most common cause is a failed MAP sensor. Other causes include wiring or connector problems (open/shorted circuit) that pull the signal to ground, a missing 5 V reference or ground at the sensor, or a blocked vacuum port. Loose or corroded connectors can also cause it. In rare cases a faulty PCM can cause this code.
Can a vacuum leak cause P0107?
Typically a vacuum leak makes manifold pressure rise (lean condition) and often sets lean codes, not P0107. A simple vacuum leak usually increases MAP voltage. P0107 (low input) usually means an electrical fault. However, if a hose to the MAP sensor is disconnected or reversed, it could create an unusually low sensor reading. In practice, most vacuum leaks trigger high-voltage or lean-related codes rather than P0107.
Can I still drive with a P0107 code?
The car may drive (often in limp mode), but performance and drivability will suffer. The engine might run poorly, with reduced power or even stall. Many cars will go into safe/fail-safe mode (reduced power, limited speed) when P0107 is present to protect the engine. It’s best to fix the issue promptly to avoid damage (e.g. to the catalytic converter).
How do I test or diagnose a MAP sensor for code P0107?
Use a voltmeter and vacuum pump. Backprobe the MAP connector: with ignition ON (engine off), you should see ~5 V on the reference wire and ~0 V on ground. The signal wire should read high (~4.5–5 V) at KOEO. Start the engine or apply vacuum: the MAP output should decrease smoothly. For example, one guide shows ~4.5 V at KOEO, ~3.75 V at 5 inHg vacuum, and ~1.0 V at 20 inHg. If the output stays near 0 V or doesn’t change with vacuum, the sensor or wiring is likely bad.
What is the difference between P0107 and P0108?
P0107 is “MAP/BARO Circuit Low Input,” meaning the MAP sensor voltage is too low. P0108 is “MAP/BARO Circuit High Input,” meaning the MAP sensor voltage is too high. In other words, P0107 = sensor sees near-zero pressure, P0108 = sensor reads above the normal max pressure range.
Will a P0107 code cause poor fuel economy?
Yes. Since the MAP sensor is critical for calculating fuel delivery, an incorrect low reading can confuse the ECM and cause poor mixture control. The engine may run very lean or rich intermittently, hurting fuel economy. Fixing the underlying issue should restore proper fuel trim and economy.
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