An engine that stalls, hesitates or runs lean may be reacting to a bad pressure signal. The manifold absolute pressure sensor tells the engine computer how much load the engine carries. A P0107 code means that signal dropped below the lowest value the computer accepts.
This guide explains why the voltage drops, how to test each wire and which repairs fix the problem. Most cases need only a multimeter and a wiring diagram.
P0107 Code Breakdown
Every OBD-II code follows the same five-character pattern set by the SAE J2012 standard. Each character narrows down which system has the fault. This table shows what each part of the code tells you.
| Character | Meaning | What It Tells You |
|---|---|---|
| P | Powertrain | The fault is in the engine or transmission systems. |
| 0 | Generic (SAE) code | The definition is the same on every OBD-II vehicle. |
| 1 | Fuel and air metering | The fault involves the sensors that measure air and fuel. |
| 07 | Specific fault | Manifold Absolute Pressure/Barometric Pressure Circuit Low |
What the P0107 Code Means for Your Engine
The SAE J2012 standard defines the P0107 code as Manifold Absolute Pressure/Barometric Pressure Circuit Low. The manifold absolute pressure (MAP) sensor sends a voltage that falls as engine vacuum rises.
A very low voltage would mean extreme vacuum, more than a running engine can produce. When the powertrain control module (PCM) sees a voltage below its limit, it sets the code. On many vehicles, the PCM then uses a fixed backup value instead of the sensor reading.
Most MAP sensors have three wires. The PCM supplies a 5-volt reference and a ground, and the sensor returns a signal. A problem on any of these wires can pull the signal low.
Common Symptoms
A low signal tells the PCM the engine is under very light load. The PCM may cut fuel and advance timing too far. Symptoms of a P0107 code include:
- Check engine light on
- Stalling, especially at idle or when you come to a stop
- Hesitation or lack of power when you accelerate
- Lean running or lean codes such as P0171
- Engine knock or pinging under load
- Harsh or early transmission shifts on some vehicles
Engines without a mass air flow sensor tend to run worst, since they rely fully on the MAP reading.
What Causes the P0107 Code?
Electrical faults cause nearly all low input codes. These are the most common causes:
- Signal wire shorted to ground. Chafed insulation lets the wire touch the engine or body.
- Open signal wire. A broken or corroded wire stops the signal from reaching the PCM.
- Open or shorted 5-volt reference. Without the reference, the sensor cannot send a signal.
- Another sensor shorting the shared reference. Many PCMs feed several sensors from one 5-volt circuit, such as the throttle position sensor.
- Loose or corroded connector. Heat from the intake manifold wears out connector pins over time.
- Failed MAP sensor. An internal fault can drive the signal low.
- PCM failure. This is rare, so rule out wiring and the sensor first.
How to Test the Circuit
You need a digital multimeter, a scan tool and the wiring diagram for your engine. A fused jumper wire helps with one of the tests.
Check Scan Tool Readings First
With the key on and the engine off, the MAP reading should match barometric pressure. That is about 101 kPa, or 29.92 inches of mercury, at sea level. On many GM vehicles, the signal voltage reads about 4.5 volts at this point.
A reading near 0 volts with the engine off confirms the P0107 code is a real circuit fault. Also look for other low voltage codes. Several codes at once, such as a throttle position sensor low code, point to a shared reference problem.
Measure the Reference and Ground
Unplug the MAP sensor and turn the key on. Measure the reference wire at the connector. It should read close to 5 volts.
If the reference reads low or zero, check for an open or short. Unplug the other sensors on the same reference circuit one at a time. If the voltage returns when you unplug one of them, that sensor is shorted. Then measure between the reference and ground pins, which should also show about 5 volts.
Use the Jumper Test on the Signal Wire
Many GM service manuals use a simple test for the signal circuit. With the sensor unplugged, the scan tool should show a very low MAP voltage. Connect a fused jumper wire between the reference pin and the signal pin at the connector.
The scan tool should now show close to 5 volts. If it does, the wiring and PCM are good, and the sensor is likely bad. If the reading stays low, the signal wire is open or shorted between the connector and the PCM. Check your own service manual before you jumper any pins, since procedures vary by make.
Fixes That Clear the P0107 Code
Fix the fault your tests found, then clear the code and drive the vehicle. The most common repairs are:
- Repair chafed or broken wires with solder and heat shrink tubing.
- Clean or replace the connector if pins are corroded or loose.
- Replace a shorted sensor on the shared 5-volt reference.
- Clear the sensor port of oil or carbon, and replace a soft or collapsed vacuum hose.
- Replace the MAP sensor if the jumper test shows good wiring.
Choose an OEM or quality-brand sensor. A sensor with the wrong pressure range for your engine will set codes right away.
Typical Repair Costs
Repairs for the P0107 code are usually affordable. This table shows common ranges.
| Repair | DIY Cost | Typical Shop Cost |
|---|---|---|
| Connector cleaning or pigtail | $10 to $40 | $75 to $200 |
| Wiring repair | $10 to $30 | $100 to $300 |
| MAP sensor replacement | $30 to $150 | $100 to $300 |
| Diagnosis | Free with your own tools | $100 to $200 |
Codes That Often Appear Together
Low MAP voltage codes often come with related faults. These codes help you narrow the search:
- P0105: General MAP circuit malfunction
- P0106: MAP reading out of the expected range
- P0108: MAP signal too high
- P0122: Throttle position sensor low input, often a sign of a shared reference fault
- P0171: System too lean on bank 1
Related Codes
These codes often show up with this one or point to the same system:
| Code | Meaning |
|---|---|
| P0104 | Mass or Volume Air Flow “A” Circuit Intermittent/Erratic |
| P0105 | Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction |
| P0106 | Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance |
| P0108 | Manifold Absolute Pressure/Barometric Pressure Circuit High |
| P0109 | Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent |
Bringing a Low MAP Signal Back to Normal
A P0107 code means the PCM sees a voltage too low for a running engine. Shorts to ground, open wires and a failed reference cause most cases.
- Check MAP and BARO readings with the engine off.
- Measure the 5-volt reference and ground.
- Use the jumper test to check the signal wire.
- Replace the sensor only after the wiring tests good.
Frequently Asked Questions
Can a Vacuum Leak Cause a P0107 Code?
A vacuum leak raises manifold pressure, which makes the voltage go up, not down. A leak more often sets a range or performance code. A blocked or collapsed sensor hose is different. It can trap high vacuum in the line and keep the reading low, so inspect the hose on remote-mounted sensors.
Is It Safe to Drive with a Low MAP Signal?
Short trips are usually possible, but the engine may stall at stops or hesitate when you merge. Lean running and extra timing advance can also cause engine knock under load. Avoid towing and hard acceleration until the repair is done. Stop driving if the check engine light starts flashing.
Can Low Battery Voltage Set This Code?
A weak battery or failing alternator rarely sets this code directly, because the PCM makes its own steady 5-volt reference. Very low system voltage during cranking can upset several sensors at once, though. If many codes appeared after a jump start, test the battery and charging system before you chase each code.
How Long Does a MAP Sensor Last?
Many MAP sensors last well past 100,000 miles. Heat, oil vapor from the PCV system and vibration shorten their life. Sensors with a vacuum hose can also fail early when the hose cracks or fills with fuel or oil. Checking the hose during regular service helps the sensor last longer.