OBD-II Diagnostic Trouble Code
P0105 — Manifold Absolute Pressure/Barometric Pressure Circuit
P0105 is a general circuit fault for the manifold absolute pressure (MAP) or barometric pressure sensor. On diesels this is usually the intake manifold or boost pressure sensor. The ECM saw a signal it could not use, such as an open, a short, or a missing 5V reference, without a more specific high or low reading. This code has nothing to do with the MAF sensor.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Manifold Absolute Pressure/Barometric Pressure Circuit
Code
P0105
Category
Powertrain
Subsystem
Air Flow
Truck-relevant
Yes
What this means for truckers
Service within a few days on a Cummins X15, Detroit DD15, PACCAR MX-13. Performance is likely degraded. Continuing to drive without service risks additional component damage.
Before you replace parts — try this first
P0105 on the Air Flow system is most often damaged or corroded map/boost sensor connector — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Check engine light and often a power derate, because the ECM cannot measure boost and limits fueling. You may also see black smoke, poor acceleration, turbo or EGR related codes, or hard starting and rough running on gas engines.
Common causes
- CommonDamaged or corroded MAP/boost sensor connector ($50–$200)
- CommonOpen or shorted sensor wiring, including a loss of the shared 5V reference ($100–$450)
- OccasionalFailed MAP/boost sensor ($120–$400)
- RareECM reference or input failure ($900–$2500)
How to fix
Inspect the sensor connector and harness, especially near hot charge air piping
When to use: First step on every P0105
Check the 5V reference, ground and signal at the sensor with key on, engine off
When to use: To separate wiring from sensor faults; check whether other 5V sensors also have codes
Compare key-on, engine-off MAP and baro readings to local barometric pressure
When to use: When the circuit is good and the sensor may be inaccurate
Replace the MAP/boost sensor
When to use: When reference and ground are good but the signal is missing or wrong
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0100 — Mass or Volume Air Flow Circuit
- → P0101 — Mass or Volume Air Flow Circuit Range/Performance
- → P0102 — Mass or Volume Air Flow Circuit Low Input
- → P0103 — Mass or Volume Air Flow Circuit High Input
- → P0104 — Mass or Volume Air Flow Circuit Intermittent
Frequently Asked Questions
Can I drive with code P0105?
P0105 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix P0105 on a commercial truck?
Total repair cost ranges $50–$2500 depending on the root cause. The cheapest fix is usually the first one listed below — Damaged or corroded MAP/boost sensor connector — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0105 fail a DOT inspection?
P0105 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between P0105 and related codes?
P0105 is closely related to: P0100 (Mass or Volume Air Flow Circuit), P0101 (Mass or Volume Air Flow Circuit Range/Performance), P0102 (Mass or Volume Air Flow Circuit Low Input), P0103 (Mass or Volume Air Flow Circuit High Input). These codes share the same subsystem (air-flow) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0105 is set without the companions, the issue is more isolated.
How do I prevent P0105 from coming back after a repair?
For P0105 (Manifold Absolute Pressure/Barometric Pressure Circuit), prevention centers on the air flow system. Service air filter on time. Clean MAF sensor at every air filter change. Inspect intake boots/hoses for cracks — vibration kills them eventually.