P0108 on 2018-2019 Ford Explorer 3.5L EcoBoost: Known MAP Sensor Failure (TSB 19-2212)

What's Unique About the 2018-2019 Ford Explorer

For this specific vehicle and engine, the P0108 code is a well-documented and known issue. Ford issued Technical Service Bulletins (TSB 19-2183, later updated to 19-2212) acknowledging that a faulty Manifold Absolute Pressure and Temperature (MAPT) sensor is the direct cause. This makes diagnosis much more straightforward than on other vehicles, where causes could range from wiring faults to vacuum leaks. The failure often triggers a cascade of other warning lights, like 'Service AdvanceTrac', because the stability control system relies on accurate engine torque data, which becomes unreliable due to the faulty sensor. The PCM then disables these dependent systems as a precaution.

Symptoms You May Notice

• Significant lack of power or sluggish acceleration, may feel like a transmission issue
• Check Engine Light (Malfunction Indicator Lamp) is on
• Powertrain Malfunction (Wrench) light is on
🎬 See how a faulty sensor triggers the wrench light and fix.
• "Service AdvanceTrac" message on the dashboard
• "Hill Start Assist Not Available" message
• Rough or unstable idle
• Poor fuel economy
• Hesitation or stalling, especially when accelerating from a stop

Most Likely Causes

1. Faulty Manifold Absolute Pressure and Temperature (MAPT) Sensor 🔴 High Probability → Shop Manifold Absolute Pressure Sensor This is a known, widespread failure point documented by Ford in Technical Service Bulletins 19-2183 and 19-2212 for the 3.5L EcoBoost engine in this specific year range. The TSB was issued due to a high failure rate of this specific sensor.
   How to confirm: Use a scan tool with the Key On, Engine Off. Per TSB 19-2183, compare the MAP (PRESS) PID to the BARO (PRESS) and TCBP (PRESS) PIDs. If the MAP reading differs by more than 10.35 kPa (1.5 psi), the sensor is faulty. A simpler check is to look for a MAP voltage reading at or above 4.5 volts with the key on and engine off.
   Typical fix: Replace the MAPT sensor located on top of the intake manifold. It is held by a single T20 Torx screw. 🎬 Watch this quick walkthrough to see the sensor replacement process. The engine cover must be removed for access. A small amount of dielectric grease or motor oil on the new sensor's O-ring is recommended for easier installation.
   Est. part cost: $90-$190

Rare But Worth Checking

• Wiring or Connector Issue: While possible, this is far less common than sensor failure on this platform. Before replacing the sensor, it is good practice to inspect the connector for visible damage, corrosion, or loose pins. If a new sensor does not resolve the issue, the wiring harness (checking for 5V reference, ground, and signal integrity) should be inspected.

Diagnosis Steps

1. Scan for diagnostic trouble codes. Confirm P0108 is present, and check for P0107 or P0109, which point to the same root cause.
2. Visually inspect the MAPT sensor connector and nearby wiring for any obvious signs of damage, corrosion, or looseness. The connector is on top of the intake manifold.
3. Using a capable scan tool with the key on and engine off, compare the Manifold Absolute Pressure (MAP) reading to the Barometric Pressure (BARO) reading. Per Ford's TSB, if they differ by more than 1.5 PSI (10.35 kPa), the MAPT sensor is confirmed to be faulty.
4. Alternatively, with a scan tool or multimeter, check the MAP sensor signal voltage with the key on, engine off. A reading at or near 5 volts indicates a failed sensor.
5. If the diagnostic test confirms a faulty sensor, proceed with replacement. If the readings are within spec, a more thorough diagnosis of the wiring (checking for 5V reference, ground, and signal integrity) may be needed, but this is highly unlikely for this vehicle.

Parts You'll Likely Need

• Manifold Absolute Pressure and Temperature (MAPT) Sensor (OEM #AA5Z-9F479-E) — This is the specific part identified by Ford in TSB 19-2212 as the cause of code P0108 on this vehicle. It is a combined pressure and temperature sensor.
  Trusted brands: Motorcraft (CX-2619), Bosch, Delphi, Standard Motor Products
  OEM price range: $90-$160
  Aftermarket price range: $50-$120

Related Codes That Often Appear With This One

• P0107 — This code for 'MAP/BARO Circuit Low' is also caused by the same failing MAPT sensor. The sensor can fail by sending a signal that is either too high (P0108) or too low (P0107). Both are cited in the same Ford TSB.
• P0109 — This code for 'MAP/BARO Circuit Intermittent' is also listed in TSB 19-2212 as a common companion code caused by the same faulty MAPT sensor sending erratic signals.

Technical Service Bulletins (TSBs) & Recalls

• TSB 19-2212: Supersedes TSB 19-2183. Identifies a faulty MAPT sensor as the cause for DTCs P0107, P0108, and/or P0109, leading to a lack of power and various warning messages on 2018-2019 Explorer, Flex, Taurus, and Lincoln MKT with the 3.5L EcoBoost engine.
• TSB 19-2183: The earlier version of the bulletin with the same core information, providing a diagnostic step to compare MAP and BARO PID values.

Platform-Specific Known Issues

• A Ford Technical Service Bulletin (TSB 19-2212, superseding 19-2183) directly addresses this code on 2018-2019 Explorers with the 3.5L EcoBoost engine, identifying a faulty MAPT sensor as the cause.
• Owner Experience: An owner on YouTube documented the repair, describing the symptoms as "sluggishness from a stop" that could feel like a transmission issue. The video confirms the ease of replacement with a single T20 Torx screw after popping off the engine cover.

Mechanic-Grade Diagnostic Values

• MAP Sensor 5V Reference Wire Voltage — expected: 4.9V to 5.1V with key on, engine off.. Failure: Voltage is near 0V or significantly below 4.9V, indicating a wiring or PCM issue.
• MAP Sensor Ground Circuit Voltage/Resistance — expected: Less than 0.1V (100mV) drop when testing voltage, or less than 0.5 Ω resistance to a known good ground.. Failure: Voltage significantly higher than 0.1V or high resistance, indicating a poor ground connection.
• MAP Sensor Signal Voltage (KOEO) — expected: For turbo applications, between 2.0V and 3.0V, and should match the BARO sensor reading.. Failure: Voltage is > 4.96V, which will trigger the P0108 DTC.
• MAP Sensor Signal Voltage (Engine Idling) — expected: Approximately 1.0V to 2.0V.. Failure: Voltage remains high, near the KOEO reading, or does not drop when the engine starts.

Scan Tool Commands That Help

• Ford IDS / FORScan / Capable Scan Tool: Reset Keep Alive Memory (KAM) — After replacing the MAPT sensor or performing other related repairs, resetting the KAM clears the PCM's adaptive learning tables. This forces the module to relearn idle, fuel trims, and sensor strategies with the new, functioning part, preventing potential lingering driveability issues.

Wiring & Ground Locations

• MAP Sensor Connector (C134) — The MAPT sensor is on top of the intake manifold. Its connector is C134, a 20-pin connector located on the left front fender apron, which can be susceptible to water intrusion.. This is the primary connector for the MAPT sensor circuit. Damage, corrosion, or water intrusion at this specific connector can cause a P0108 code even if the sensor itself is good.
• Engine Harness Chafe Point — While a recall (19S32) was for 2020+ models, a known chafe point for Ford engine harnesses is near the A/C compressor pulley.. If the wiring harness rubs against the A/C pulley or another bracket, it can short the 5V reference or signal wire to power or ground, causing P0108 or related codes. A visual inspection of the harness routing near moving components is a valid, though unlikely, diagnostic step if a new sensor doesn't fix the issue.
• Sensor Ground (G104) — On some Ford engines, a common sensor ground point is G104, located at the center rear of the engine on the intake manifold.. A loose or corroded ground at this location can affect multiple sensors, including the MAP sensor, causing erratic or biased readings that could trigger a P0108 code.

OEM Part Supersession History

• 2R3Z-9F479-AA → AA5Z-9F479-A — Part revision or manufacturer change.
• AA5Z-9F479-A → AA5Z-9F479-E — This is the current, most updated part number specified in TSB 19-2212 to resolve the P0107/P0108/P0109 issues. It is also sold under the Motorcraft number CX-2619.
  Heads up: While older parts may physically fit, using the latest 'E' revision is critical to ensure the fix is permanent, as it was released to address the high failure rate of previous versions.

Diagnostic Flowchart

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 — Manifold Absolute Pressure/Barometric Pressure Circuit Low. This is the direct counterpart to P0108 and is explicitly grouped together in Ford TSB 19-2212 and 19-2183 as being caused by the exact same faulty MAPT sensor.
• P0109 — Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent. This code is also listed in TSB 19-2212 alongside P0108 as a primary symptom of the known MAPT sensor failure on the 3.5L EcoBoost.
• P0106 — Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance. Owners have reported this code appearing concurrently with P0107, P0108, and P0109 during severe MAPT sensor or PCM failures.

Frequently Asked Questions