P0108 on 2008-2015 Mitsubishi Lancer Evolution: MAP Sensor Circuit High Causes and Fixes

What's Unique About the 2008-2015 Mitsubishi Lancer Evolution

The Lancer Evolution X is a high-performance, turbocharged vehicle from the factory. Its engine management relies heavily on accurate pressure readings for both performance and safety. While the P0108 code on a stock Evo X is typically a straightforward sensor failure, this platform is frequently modified. In the tuning community, P0108 often appears when owners increase boost pressure beyond the range of the stock 3-bar MAP sensor, forcing an upgrade to a 4-bar or 5-bar sensor and a corresponding ECU retune to prevent the code and ensure correct fueling.

Symptoms You May Notice

• Check Engine Light is on
• Rough or unstable idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Black smoke from the exhaust, indicating a rich fuel mixture
• Decreased fuel economy
• Engine may stall intermittently, especially when coming to a stop
🎬 See more: 10 common symptoms of a failing MAP sensor.

Most Likely Causes

1. Failed Manifold Absolute Pressure (MAP) Sensor 🔴 High Probability → Shop Manifold Absolute Pressure Sensor The MAP sensor is the most common failure point for this code according to Mitsubishi's own service documentation and extensive owner reports. Internal electronics can fail due to heat and vibration, causing the sensor to send a constant high voltage signal regardless of actual manifold pressure.
   How to confirm: With a scan tool, observe the live MAP sensor data. With Key On, Engine Off (KOEO), the voltage should be near 4.5V at sea level and the pressure should match barometric pressure. If the voltage is stuck at or above 4.6V, the sensor has failed. At idle, voltage should drop to 1.0-1.5V. You can also backprobe the signal wire at the sensor to check the voltage directly.
   Typical fix: Replace the MAP sensor. It is located on the intake manifold and secured with two bolts. 🎬 Watch: How to locate and replace your MAP sensor.
   Est. part cost: $220-$315
2. Wiring or Connector Issue 🟡 Medium Probability Engine vibration and heat can cause wiring to chafe or connectors to corrode over time. A short in the signal wire to the 5V reference or another power source will cause a constant high voltage reading. This can happen where the harness routes near the intake manifold.
   How to confirm: Visually inspect the wiring harness and connector for the MAP sensor. Look for any signs of damage, melting, or corrosion. Check for continuity on the ground wire and for a stable 5V reference at the connector. Check for a short between the signal wire and the power/ground wires. The connector pinout is: Pin 1 - Signal, Pin 2 - Ground, Pin 3 - 5V Reference.
   Typical fix: Repair the damaged section of the wiring harness or replace the connector pigtail. Ensure all connections are clean and secure.
   Est. part cost: $5-$30
3. Boost Level Exceeds Stock Sensor Limit (Modified Vehicles) 🟡 Medium Probability The stock MAP sensor is a 3-bar sensor, capable of reading up to approximately 29 psi of boost (absolute pressure of ~44psi). Many tunes for the 4B11T push boost levels higher than this, 'pegging' the sensor at its maximum voltage and triggering P0108.
   How to confirm: This cause is only relevant if the vehicle is tuned and running higher than stock boost. Check your tune's target boost pressure. If it exceeds ~29 psi, this is the likely cause.
   Typical fix: Install a higher-range MAP sensor (e.g., 4-bar or 5-bar from a brand like Omni Power) and have the ECU retuned to scale for the new sensor's readings.
   Est. part cost: $130-$150

Rare But Worth Checking

• Failed Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is the least likely cause. Mitsubishi lists it as a possibility, but you should exhaust all other diagnostic options before considering ECM replacement. An ECM failure would typically present with multiple, unrelated fault codes.

Diagnosis Steps

1. Connect a scan tool and verify P0108 is the primary code. Record the freeze frame data to see the engine conditions when the code was set.
2. With the key on and engine off (KOEO), view the live data from the MAP sensor. The pressure reading should be close to the atmospheric (barometric) pressure for your altitude. The voltage should be around 4.5V, not pegged at or near 5V.
3. Start the engine. At idle, the MAP sensor should read a high vacuum (low pressure value), specifically between 16-36 kPa (4.7-10.6 in. Hg). The voltage should drop to approximately 1.0-1.5V. If the reading does not change or remains high, the sensor or its circuit is faulty.
4. Turn the engine off. Locate the MAP sensor on the intake manifold. Inspect the connector and wiring for any visible damage, corrosion, or loose pins.
5. Disconnect the sensor. With the key on, use a multimeter to test the connector terminals. You should find a 5V reference on Pin 3, a good ground (near 0V) on Pin 2, and the signal wire on Pin 1.
6. If power and ground are correct, the issue is likely the sensor itself. If power or ground is missing, you have a wiring issue that needs to be traced back to the ECM.
7. If all wiring checks out and the vehicle is stock, replace the MAP sensor.
8. If the vehicle is modified with higher boost, confirm if the installed MAP sensor is adequate for the boost levels. If not, an upgraded sensor and ECU tune are required.
9. After repairs, clear the code and perform a test drive to ensure the fix was successful.

Parts You'll Likely Need

• Manifold Absolute Pressure (MAP) Sensor (OEM #1865A052) — This is the most common cause of P0108 on a stock vehicle, as confirmed by Mitsubishi service documents and numerous owner forums.
  Trusted brands: Mitsubishi Genuine, Omni Power (for modified vehicles), Tridon (Aftermarket)
  OEM price range: $210-$315
  Aftermarket price range: $130-$180

Platform-Specific Known Issues

• Owner Experience: Intermittent P0108 due to wiring: On the EvolutionM.net forums, a user reported chasing an intermittent P0108 code that would appear and disappear. After replacing the MAP sensor did not solve the issue, a thorough inspection of the wiring harness revealed a section near the intake manifold that had rubbed through and was intermittently shorting the signal wire to the 5V reference wire, causing the high voltage reading. Repairing the damaged wires permanently resolved the code.

Mechanic-Grade Diagnostic Values

• MAP Sensor Signal Voltage (DTC Trigger) — expected: < 4.6V. Failure: Voltage is > 4.6V for more than 2 seconds.
• MAP Sensor Pressure at Idle — expected: 16 - 36 kPa (4.7 - 10.6 in. Hg). Failure: Pressure reading is significantly higher or does not change from KOEO value.
• MAP Sensor Ground Wire Voltage (Backprobed at connector) — expected: < 0.5V. Failure: Voltage is > 0.5V, indicating a poor ground connection from the ECM.
• MAP Sensor Signal Voltage at Idle — expected: Approx. 1.0V - 1.5V. Failure: Voltage remains high (near 4.5V), indicating no response to engine vacuum.

Wiring & Ground Locations

• MAP Sensor Connector (B-14 or B-117 in service manuals) — On the intake manifold.. This is the primary connection point to test. The pinout is critical for diagnosis. Pin 1 is the signal wire to ECM pin 45. Pin 2 is the ground wire from ECM pin 46. Pin 3 is the 5V reference from ECM pin 44. The ground is provided by the ECM, not a chassis ground.

Real Owner Repair Stories

• EvolutionM.net forum user 'MalibuJack' (Evo (thread from 2004, but concept applies to piggyback ECUs)) — Intermittent P0108 code.
  ❌ Tried (didn't work) Initial diagnosis was unclear.
  ✅ What actually fixed it The issue was caused by an aftermarket UTEC piggyback ECU. If the car was started before the UTEC fully initialized, it would throw the P0108 code. The fix was to wait for the UTEC to fully boot (e.g., wait for CEL blink to stop) before cranking the engine.

OEM Part Supersession History

• 1865A052 → N/A — This part number appears to be stable and was used for the entire 2008-2015 production run for the Lancer Evolution.

Model Year Variations Within This Range

• 2008-2015: While the physical MAP sensor (1865A052) and its wiring are consistent across all model years, tuners should be aware that the ECU ROM ID can differ by year and model (GSR/MR). When upgrading to an aftermarket MAP sensor, the specific patch or scaling data applied to the tune may depend on the ROM ID being used.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Active Yaw Control (AYC/ACD) Pump Failure 🔴 High — Very common, especially on vehicles in regions with road salt. Corrosion causes the pump assembly to fail, leading to an 'AWD Service Required' light. Can occur at any mileage but is more frequent on older models. (Ref: No specific recall, but a widely known failure.)
• Timing Chain Stretch 🔴 High — Can occur on higher mileage (60k+ miles) or poorly maintained engines. The ECU can detect stretch and will post a 'Timing Chain Service Required' warning. If ignored, it can lead to jumped timing and catastrophic engine damage. (Ref: TSB-11-11-004 Rev. B addresses procedures for checking chain elongation and reprogramming the ECU to adjust detection parameters.)
• Clutch Master Cylinder (CMC) Failure 🟠 Medium — Common across 2008-2013 models. The original plastic CMC can fail, leading to a loss of clutch pressure, inability to shift, and a soft pedal. (Ref: NHTSA Recall #13V446000 was issued for dealers to replace the faulty CMC with an updated part.)
• Failing Fuel Pump Relay 🔴 High — Common on earlier models (2008-2012). The original black relay fails, causing the fuel pump to not switch to its high-flow mode under load. This leads to a dangerously lean air-fuel mixture and can cause engine damage. (Ref: This was a service campaign, not a formal recall. Mitsubishi provided updated blue (8627A024) or green relays to replace the faulty black ones.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, buying a used MAP sensor is NOT recommended. It is a sensitive electronic component exposed to significant heat and vibration. The risk of getting a part that is already failing or has a reduced lifespan is high, and the cost savings do not justify the potential for continued diagnostic headaches.

What to inspect on the donor part:

• Not applicable as used purchase is not recommended.

OEM-only on this vehicle (don't cheap out):

• Engine Control Module (ECM) - If the ECM is determined to be the fault, a new or professionally refurbished unit with a warranty is the only reliable option.

Aftermarket brands forum-validated for this vehicle:

• Omni Power: This is the most widely accepted and used brand for upgraded 4-bar or 5-bar MAP sensors in the Evo X tuning community.

Brands owners have reported issues with on this vehicle:

• Unnamed or generic 'white box' sensors from online marketplaces. While cheap, their accuracy, scaling, and durability are often poor, leading to tuning difficulties and unreliable engine performance.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0107 — The low-voltage counterpart to P0108, often caused by the same MAP sensor failure or circuit issues (open ground vs. short to power).
• P0172 — Rich fuel mixture code; P0108 causes the ECU to see high manifold pressure, leading to excessive fuel injection and black smoke.
• P0012 — Related to timing issues; while P0108 is a sensor code, timing chain stretch (a known 4B11T issue) can cause engine instability similar to MAP sensor failure symptoms.
• U0100 — Lost communication with ECM; can appear if wiring harness damage near the intake manifold affects the CAN bus or main ECU power/ground shared with the MAP sensor.

Frequently Asked Questions