P0106 – Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance

P0106 is a very common check engine light code that points to a problem with how your engine measures and reacts to air pressure. When this code sets, your car’s computer is telling you it doesn’t trust the signal coming from the MAP (manifold absolute pressure) sensor. That can lead to rough running, poor fuel economy, and even stalling if you ignore it. In this guide, you’ll learn what P0106 actually means, the usual causes, symptoms to watch for, and how you or your mechanic can diagnose and fix it correctly.

What Does P0106 Mean?

P0106 stands for “MAP/Barometric Pressure Circuit Range/Performance.” In plain terms, the engine control unit (ECU) is seeing a MAP sensor signal that doesn’t make sense compared to engine RPM, throttle position, or barometric pressure. The voltage is not necessarily too high or too low all the time, but it’s behaving in a way the ECU considers unrealistic.

The MAP sensor tells the ECU how much air is entering the engine by measuring pressure in the intake manifold. If that signal is erratic, delayed, or out of the expected range, the ECU can’t calculate fuel and ignition correctly, so it sets P0106 and usually turns on the check engine light.

Quick Reference

• Code: P0106
• Definition: MAP/Barometric Pressure Circuit Range/Performance
• Main component: MAP sensor and its wiring
• Typical symptoms: Rough idle, poor fuel economy, hesitation, hard starting
• Risk level: Moderate – usually drivable but can worsen quickly
• Common fix: Repair vacuum leaks or replace faulty MAP sensor

Real-World Example / Field Notes

In the shop, P0106 often shows up on vehicles that come in for a rough idle and bad fuel mileage after a DIY air filter or intake job. A good example: a small SUV arrived with a fresh aftermarket intake tube and a check engine light. The MAP sensor was loosely installed and the intake tube had a small crack near a clamp. On the scan tool, MAP readings jumped around at idle. After fixing the air leak and securing the sensor, the readings stabilized and P0106 cleared for good.

Symptoms of P0106

• Check engine light on: P0106 usually sets a steady MIL, sometimes with other air/fuel codes.
• Rough idle: The engine may shake, surge, or feel like it’s “hunting” for the right idle speed.
• Poor fuel economy: You may notice more frequent fuel stops or a strong fuel smell from a rich mixture.
• Hesitation or stumble: Acceleration can feel flat, delayed, or jerky when you press the gas.
• Hard starting: The engine may crank longer than normal, especially when hot or cold.
• Black exhaust smoke: In more severe cases, a rich mixture can cause dark exhaust and soot on the tailpipe.
• Occasional stalling: At stops or during sudden deceleration, the engine might stall unexpectedly.

Common Causes of P0106

Most Common Causes

• Faulty MAP sensor: Internal failure, contamination from oil vapors, or water intrusion can cause erratic voltage signals.
• Vacuum leaks: Cracked vacuum hoses, leaking intake manifold gaskets, or a loose intake tube can skew manifold pressure readings.
• Wiring or connector issues: Corroded terminals, broken wires, or loose connectors at the MAP sensor can cause intermittent or noisy signals.
• Improperly installed intake parts: Aftermarket intakes, throttle body spacers, or recent engine work can leave clamps loose or sensors mispositioned.
• Clogged or restricted intake path: Severely dirty air filters or collapsed intake ducts can affect pressure behavior in the manifold.

Less Common Causes

• Barometric pressure sensor issues: On some vehicles, BARO is built into the MAP or ECU; if BARO is off, P0106 can set.
• ECU software or internal fault: Rarely, outdated software or a failing ECU can misinterpret a good MAP signal.
• Exhaust restrictions: A partially plugged catalytic converter can alter engine load and make MAP readings look abnormal.
• Incorrect engine modifications: Big cams, forced induction, or poorly tuned aftermarket parts can confuse factory MAP logic if not tuned properly.
• Ground or power supply problems: Low system voltage, bad grounds, or a shared sensor 5V reference issue can throw off MAP data.

Diagnosis: Step-by-Step Guide

To diagnose P0106 properly, you’ll want at least a basic OBD2 scan tool, a digital multimeter, and, ideally, access to live data. A smoke machine and a wiring diagram are very helpful if you’re chasing vacuum leaks or electrical issues. If you’re comfortable with Mode $06 data, that can also help confirm borderline sensor performance.

1. Confirm the code and check for companions. Scan the vehicle and note any additional codes (like P0105, P0107–P0108, lean/rich codes, or misfires). Multiple codes can point you toward vacuum leaks or power/ground issues.
2. Inspect the intake system visually. With the engine off, check the air filter box, intake tube, clamps, and hoses. Look for cracks, loose clamps, disconnected vacuum lines, or oil contamination around the MAP sensor.
3. Inspect the MAP sensor and connector. Unplug the sensor and look for bent pins, corrosion, moisture, or oil inside the connector. Make sure the sensor is mounted firmly and sealed to the manifold or intake.
4. Check MAP live data at key-on and idle. With the key on/engine off, MAP reading should be close to local barometric pressure (often around 100 kPa or 14.5 psi at sea level). At idle, the reading should drop significantly due to engine vacuum (typically 25–45 kPa). If readings don’t change or jump around, suspect the sensor or wiring.
5. Verify sensor 5V reference and ground. Using a multimeter, back-probe the MAP connector. You should see about 5V on the reference wire and near 0V on the ground. Poor ground or missing 5V will cause unstable readings and P0106.
6. Check MAP signal voltage response. With the engine idling, gently snap the throttle while monitoring MAP voltage or kPa on the scan tool. The reading should respond smoothly, increasing quickly when you rev and returning to a stable value at idle. Erratic spikes or flat lines indicate a bad sensor or wiring.
7. Test for vacuum leaks. Listen for hissing, spray around suspect areas with carb cleaner (carefully) and watch for RPM changes, or use a smoke machine. Pay attention to intake gaskets, brake booster hose, and PCV lines.
8. Check for exhaust or engine load issues. If MAP, wiring, and vacuum all check out, but the engine feels restricted or weak, inspect the exhaust for restrictions and verify basic engine health (compression, timing).
9. Review freeze-frame and Mode $06 data. Look at the conditions when P0106 set (RPM, load, throttle). Mode $06 can show if the MAP sensor is failing a rationality test even when readings look okay at idle.
10. Substitute a known-good MAP sensor if needed. If all external factors check out and the signal is still suspect, replacing the MAP with a quality OEM or equivalent unit is often the final confirmation.

Pro tip: Always clear the code and perform a proper road test with live data after repairs. Watch MAP, throttle position, and RPM together. You want smooth, consistent changes without sudden spikes or dropouts.

Possible Fixes & Repair Costs

Fixing P0106 usually involves addressing either a bad sensor or an air leak. Common repairs include replacing the MAP sensor, repairing or replacing cracked vacuum hoses, tightening or replacing intake tubes, cleaning corroded connectors, or in rare cases updating ECU software. At a typical repair shop, you might spend around $50–$150 for simple hose or connection repairs, $120–$350 for MAP sensor replacement, and $300–$800 or more if intake gaskets or deeper engine work is needed. Labor rates, vehicle design, and part quality all affect the final cost.

Can I Still Drive With P0106?

In many cases, you can still drive with P0106, but it’s not something you should put off for long. If the engine runs relatively smooth and only the check engine light is on, short trips to get it diagnosed are usually fine. However, if you notice severe rough running, stalling, heavy black smoke, or a strong fuel smell, you should avoid driving and have the vehicle towed. Driving too long with a rich or lean mixture can damage the catalytic converter and other components.

What Happens If You Ignore P0106?

If you ignore P0106, the ECU will continue to rely on faulty MAP information, which can lead to long-term rich or lean operation. Over time, that can foul spark plugs, overheat and damage the catalytic converter, reduce fuel economy, and cause more frequent stalling or misfires. What starts as a relatively simple sensor or vacuum issue can turn into a much more expensive repair if left unchecked.

Related Pressure Manifold Codes

Compare nearby pressure manifold trouble codes with similar definitions, fault patterns, and diagnostic paths.

• P0109 – Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
• P0108 – Manifold Absolute Pressure/Barometric Pressure Circuit High Input
• P0107 – Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
• P0105 – Manifold Absolute Pressure/Barometric Pressure Circuit
• P051B – Crankcase Pressure Sensor Circuit Range/Performance
• P2020 – Intake Manifold Runner Position Sensor/Switch Circuit Range/Performance Bank 2

Key Takeaways

• P0106 means the ECU doesn’t trust the MAP sensor signal because it’s out of expected range or behaving inconsistently.
• Common causes include a failing MAP sensor, vacuum leaks, and wiring or connector problems.
• Symptoms range from a simple check engine light to rough idle, poor fuel economy, hesitation, and stalling.
• Diagnosis involves checking live data, verifying 5V reference and ground, inspecting for vacuum leaks, and confirming sensor response.
• Repairs are often affordable if caught early, but ignoring P0106 can damage the catalytic converter and increase repair costs.

Vehicles Commonly Affected by P0106

P0106 shows up across many makes and models because almost every modern engine uses a MAP or combined MAP/BARO sensor. In the field, this code is especially common on GM vehicles (Chevrolet, GMC, Buick), Chrysler/Dodge/Jeep products, and many Hyundai and Kia models. It also appears regularly on Honda, Toyota, Ford, and VW/Audi engines, particularly on higher-mileage vehicles or those with aftermarket intakes. Compact cars, small SUVs, and pickup trucks with plastic intake manifolds and multiple vacuum hoses tend to be frequent visitors for this code.

FAQ

Can a dirty air filter cause P0106?

A very dirty or restricted air filter can contribute to abnormal airflow and pressure behavior in the intake, which might help trigger P0106, especially if other issues are present. However, by itself, a dirty filter is more likely to cause performance loss than directly cause this code. It’s still smart to inspect and replace the air filter if it’s overdue.

Is P0106 the same as a bad MAF sensor?

No, P0106 is specifically related to the MAP/Baro pressure circuit, not the MAF sensor. Some vehicles use both sensors, and problems with one can affect how the ECU interprets the other, but the code itself points you to the MAP system. You should diagnose the MAP circuit first before replacing any MAF components.

Can I clear P0106 and keep driving if it goes away?

You can clear the code and see if it returns, but if the underlying issue is still there, P0106 will usually come back within a few drive cycles. If the code returns, you should treat it as a real problem and diagnose it properly rather than repeatedly clearing it. Repeated clearing also erases valuable freeze-frame data that helps pinpoint the cause.

How do I know if my MAP sensor is really bad?

A bad MAP sensor often shows unstable or unrealistic readings on a scan tool compared to engine behavior. If the 5V reference and ground are good, there are no vacuum leaks, and the signal still jumps around or doesn’t change with RPM, the sensor is likely faulty. Substituting a known-good sensor or checking Mode $06 data can confirm a borderline sensor.

Can low battery voltage cause P0106?

Yes, low system voltage or charging problems can affect sensor reference voltages and ECU operation, which may indirectly trigger P0106. If you’re seeing multiple random sensor codes along with P0106, it’s smart to check battery health, alternator output, and main grounds before chasing individual sensors.