P0107 Code: Manifold Absolute Pressure/Barometric Pressure Circuit Low Input

What the P0107 code means

The MAP sensor delivers a signal proportional to manifold pressure, and it moves within a limited range. At the low end it never reaches zero volts, and at the high end it never reaches five. Those margins exist precisely to tell a real measurement apart from an electrical fault.

The P0107 code is set when the signal falls below that minimum, typically below 0.2 volts. No operating condition produces that value, not even the maximum vacuum the engine can generate.

That is why this code is not diagnosed by watching how the engine behaves but by measuring the circuit. The three possibilities are a signal wire that is cut or touching ground, a missing five volt supply, or a sensor that is broken inside.

Without that reading the computer falls back on a calculated backup value, so the engine keeps running but with much lower accuracy. That is where the high fuel use and the lazy response come from.

There is a test that tells you in a minute whether the problem is in the sensor or in the wiring. With the sensor unplugged and the key on, briefly connect the five volt reference pin to the signal pin: the scan tool reading should shoot up to the maximum. If it does, the wiring to the computer is intact and the sensor is the bad part. If it does not move, the problem is in the signal wire or in the computer itself.

P0107 code symptoms

• Check engine light on.
• Loss of power and a lazy response to the throttle.
• Unstable idle, or an engine that stalls.
• Hard starting.
• A noticeable increase in fuel use.
• Black smoke when accelerating.
• Possible limp mode.
• An absurd or zero pressure reading on the scan tool.
• A pressure reading of zero even with the key on and the engine off.
• Other sensors affected at the same time if the five volt reference is down.

Likely causes of the P0107 code

1. Signal wire cut or shorted to ground.
2. Five volt reference missing, which usually affects other sensors too.
3. MAP sensor failed internally.
4. Connector unplugged, with backed-out pins or with moisture.
5. Sensor ground with high resistance or open.
6. Wiring damaged by rubbing or heat.
7. Water in the connector after an engine wash.
8. Damaged input stage in the computer. Uncommon, and checked last.
9. Another shorted sensor pulling down the shared reference and affecting the MAP as well.

How to diagnose the P0107 code step by step

1. Watch the reading with the key on and the engine off. It should show atmospheric pressure. A value of zero confirms the electrical fault.
2. Check the five volt reference at the sensor connector. If it is missing, see whether other sensors are affected too, because that line is usually shared.
3. Measure the voltage on the signal wire with the sensor unplugged. If it stays at zero, the wire is cut or shorted to ground.
4. Verify the continuity of the sensor ground and its voltage drop.
5. Rule out a short to ground on the signal wire with the computer connector unplugged.
6. Inspect the connector for water, green corrosion and backed-out pins.
7. Wiggle the harness with the key on and watch the reading.
8. Find out whether the engine was washed recently, a common reason for water in the connector.
9. Briefly connect the 5 volt reference to the signal pin with the sensor unplugged. If the reading shoots to the maximum, the wiring is good and the sensor is the bad part.
10. Check for codes from other sensors, because they share the reference and a single short pulls it down for all of them.

How to fix the P0107 code

• Repair the signal wire that is cut or shorted to ground with solder and heat-shrink tubing.
• Restore the five volt reference by finding the short that is loading it down.
• Replace the MAP sensor if the circuit is good and it still sends no signal.
• Dry and clean the connector, and protect it with dielectric grease.
• Repair the sensor ground down to bare metal.
• Protect the repaired section of wiring so it does not rub again.
• Find the shorted sensor that is loading down the shared reference before you replace the MAP.

After the repair, check with the key on that the sensor reads the atmospheric pressure for your altitude.

Technical reference data

• Typical signal: 0.5 to 4.5 volts. Below 0.2 volts sustained sets the code.
• With the key on and the engine off it should read atmospheric pressure: about 101 kPa (14.7 psi) at sea level.
• Reference supply: 5 volts, usually shared with other sensors.
• Allowable ground voltage drop: below 0.2 volts.
• P0108 is the opposite code: voltage too high.
• Jumper test between reference and signal: the reading should shoot to the maximum if the wiring is intact.

Brand-specific notes

If the five volt reference is missing, first check for codes from other sensors. That line is shared, and a single shorted sensor can pull it down for all of them, producing several codes that look like independent failures.

Water in the connector after a pressure wash is a very common cause of the P0107 code and an easy one to rule out: dry it, plug it back in and clear the code before you buy anything.

Frequently asked questions about P0107