P0106 on 2011-2019 Ford Explorer 3.5L: MAP Sensor and Vacuum Leak Guide

What's Unique About the 2011-2019 Ford Explorer

For this generation of Ford Explorer, the 3.5L Cyclone V6 is particularly prone to vacuum leaks from brittle plastic tubing, as noted in real-world owner complaints filed with the NHTSA. [ODI #10967364] While the MAP sensor itself can fail, a thorough inspection of all vacuum lines, especially the PCV hoses and a specific vacuum harness that serves the EGR and fuel pressure sensor, should always be the first step. Additionally, Ford issued TSBs for similar models of this era (like TSB 13-9-8) for identical symptoms caused by faulty wiring splices, indicating that wiring should be inspected carefully if a vacuum leak or bad sensor isn't obvious. Some owners report that cleaning a dirty throttle body and performing an idle relearn procedure can also resolve the code, especially after a battery disconnect.

Symptoms You May Notice

• Check Engine Light illuminated
• Hesitation or stumbling during acceleration
• Rough or unstable idle
• Noticeable loss of engine power
• Difficulty starting the engine
• Decreased fuel economy
• Engine stalling, particularly when coming to a stop.
• Black smoke from the exhaust.

Most Likely Causes

1. Faulty Manifold Absolute Pressure (MAP) Sensor 🔴 High Probability Oil vapor from the PCV system can contaminate the sensor's diaphragm over time, causing it to send slow or incorrect readings. Electronic failure is also common. This is the most frequent cause if a vacuum leak is not present.
   How to confirm: With a scan tool, monitor MAP sensor voltage with Key On, Engine Off (KOEO). The reading should be close to the BARO sensor reading (approx. 4.5V at sea level). At idle, voltage should drop to 1.0-1.8V. If readings are stuck, erratic, or don't change with throttle input, the sensor is likely bad. The sensor is located on the intake manifold.
   Typical fix: Replace the MAP sensor. It is located on the intake manifold and is typically held in by a single bolt. Ensure the o-ring is properly seated on the new sensor to prevent a vacuum leak.
   Est. part cost: $40-$100
2. Cracked or Leaking Vacuum Hoses 🔴 High Probability As cited in NHTSA complaints, the plastic and rubber vacuum lines used on this engine can become brittle and crack over time due to heat and age, causing unmetered air to enter the intake manifold. [ODI #10967364] A specific vacuum harness that connects to the intake, EGR valve, and fuel pressure sensor is a known failure point.
   How to confirm: Visually inspect all vacuum hoses connected to the intake manifold, especially the PCV lines and their elbow connectors. Listen for a hissing sound at idle. The most effective method is to perform a smoke test to pinpoint the exact location of the leak.
   Typical fix: Replace the damaged hose, elbow, or the entire vacuum harness assembly.
   Est. part cost: $15-$60
3. Dirty or Failing Electronic Throttle Body (ETB) 🟡 Medium Probability The PCV system routes oil vapor and crankcase gases into the intake, which can cause carbon and oil sludge to build up around the throttle plate. This buildup restricts airflow and can disrupt the pressure readings within the manifold, especially at idle. This issue is common enough that Ford faced lawsuits and extended warranties for throttle body failures on this platform.
   How to confirm: Remove the air intake tube connected to the throttle body and visually inspect the throttle bore and plate for significant carbon buildup. The vehicle may also exhibit sudden power loss or enter 'limp mode' with codes like P2111 or P2112.
   Typical fix: Clean the throttle body bore and plate using a dedicated throttle body cleaner and a soft cloth. After cleaning or disconnecting the battery, an idle relearn procedure may be necessary: let the vehicle idle for about 10 minutes without touching the accelerator.
   Est. part cost: $10 for cleaner, $150-$300 for a new ETB
4. Damaged Wiring or Electrical Connector ⚪ Low Probability Ford TSB 13-9-8 for related models points to issues with signal return splices in the engine wiring harness causing identical symptoms, suggesting a potential weak point in the harness design of this era. Wires can also be damaged by heat or chafing.
   How to confirm: Inspect the MAP sensor connector for corrosion, bent pins, or loose connections. Trace the wiring harness back as far as possible, looking for any signs of chafing, melting, or breaks. Use a multimeter to confirm a 5-volt reference, good ground, and a changing signal voltage at the connector.
   Typical fix: Repair the damaged section of wiring or replace the connector pigtail.
   Est. part cost: $15-$40

Rare But Worth Checking

• Restricted Catalytic Converter: A severely clogged catalytic converter can create excessive exhaust backpressure, which alters the pressure in the intake manifold and can trigger a P0106 code. This is usually accompanied by a severe loss of power, especially at high RPMs, and potentially a sulfur or 'rotten egg' smell.
• High-Altitude Glitch: Ford has issued TSBs (like #SSM 50156 and #SSM 49446) for newer models where a P0106 code can be stored after the vehicle is transported to a higher altitude with the key off. The fix is simply to clear the code. While for a newer model, it indicates a sensitivity in Ford's programming that could potentially affect this generation.

Diagnosis Steps

1. Read all stored DTCs with an OBD-II scanner to check for other related codes.
2. With a scan tool, view live data. With Key On, Engine Off (KOEO), compare the MAP sensor reading to the BARO sensor reading. They should be nearly identical (within 6 kPa).
3. Start the engine. At idle, the MAP sensor voltage should drop to between 1.0V and 1.8V. The reading should increase smoothly towards 4.5V as you open the throttle.
4. If sensor data seems correct, perform a thorough visual inspection of the engine bay. Listen for an audible hissing sound around the top of the engine, which would indicate a significant vacuum leak.
5. Thoroughly inspect all vacuum hoses and plastic lines connected to the intake manifold for any cracks, breaks, or loose connections. Pay close attention to the PCV hoses and the multi-line harness that connects to the EGR valve.
6. If no obvious leaks are found, perform a smoke test to identify hard-to-see cracks in the intake system.
7. Inspect the MAP sensor's electrical connector for corrosion, moisture, or damage. Ensure it is seated securely.
8. Remove the air intake duct and inspect the electronic throttle body for heavy carbon buildup. Clean if necessary and perform an idle relearn procedure.
9. If the scan tool data is erratic or incorrect and all wiring/vacuum lines are confirmed good, replace the MAP sensor.

Parts You'll Likely Need

• Manifold Absolute Pressure (MAP) Sensor (OEM #AA5Z-9F479-C) — This sensor is a primary cause of the P0106 code, either through electronic failure or contamination from the PCV system. The OEM part number is AA5Z-9F479-C.
  Trusted brands: Motorcraft, Bosch, Standard Motor Products, NTK
  OEM price range: $70-$110
  Aftermarket price range: $40-$80
• PCV Hose / Vacuum Line — Brittle plastic vacuum lines are a known failure point on this platform and a very common cause of this code, as documented in NHTSA complaints and owner forums. [ODI #10967364, 43]
  Trusted brands: Motorcraft, Dorman
  OEM price range: $30-$60
  Aftermarket price range: $15-$40

Related Codes That Often Appear With This One

• P0401 — An owner complaint to the NHTSA reported P0106 and P0401 (EGR Flow Insufficient) together, likely caused by a broken plastic vacuum line that served both the MAP sensor and the EGR system. [ODI #10967364, 46]
• P0107 — This code indicates 'MAP Circuit Low Input,' pointing directly to a problem in the same circuit, such as a short to ground or a failed sensor.
• P0108 — This code indicates 'MAP Circuit High Input,' pointing to an open circuit, a sensor stuck at a high reading, or a wiring issue.

Technical Service Bulletins (TSBs) & Recalls

• TSB 13-9-8: Addresses drivability concerns like hesitation and lack of power on 2012-2014 models, which are linked to P0106 in NHTSA complaints, and points to a wiring splice as a potential cause.
• SSM 50156: Notes that P0106 may be stored after key-off transportation to higher altitudes on some Ford vehicles; the fix is to clear the DTC.

Platform-Specific Known Issues

• NHTSA ODI #10967364: An owner of a 2010 model reported codes P0106 and P0401 caused by 'plastic tubing [that] failed by breaking (disintegrating really),' highlighting the common issue of brittle vacuum lines.
• NHTSA ODI #10787972: A 2012 Explorer owner reported P0106 accompanied by hesitation, loss of idle, and lack of power, and referenced Ford TSB #13-9-8, which points to wiring harness issues on similar platforms.

Mechanic-Grade Diagnostic Values

• MAP vs. BARO Sensor Correlation (KOEO) — expected: Readings should be nearly identical (within 6 kPa or ~0.8 PSI) of each other.. Failure: A significant difference between the MAP and BARO readings with the engine off indicates a faulty MAP sensor.
• MAP Sensor Signal Voltage (KOEO) — expected: ~4.5 - 4.8V at sea level. Voltage decreases with higher altitude.. Failure: Voltage significantly lower than expected (e.g., 3.9V at sea level) points to a faulty sensor.
• MAP Sensor Signal Voltage (Engine Idling) — expected: 1.0V - 1.8V at normal idle.. Failure: Voltage is stuck high (near KOEO reading) or does not change when the throttle is snapped.
• MAP Sensor 5V Reference Voltage — expected: 4.8V - 5.2V at the sensor connector with KOEO.. Failure: No voltage or low voltage indicates a wiring or PCM issue, not a sensor failure.
• MAP Sensor Ground Circuit Voltage — expected: Less than 0.1V (100mV) at the sensor connector.. Failure: Higher voltage indicates a poor ground connection, which can cause incorrect sensor readings.

Scan Tool Commands That Help

• Ford IDS, FORScan: Datalogger: Graph MAP, BARO, RPM, TP PIDs — To visually confirm if the MAP sensor signal is responding correctly and smoothly to changes in engine RPM and throttle position, or if it is lagging, sticking, or providing erratic data.
• Ford IDS, FORScan: Clear/Reset Keep Alive Memory (KAM) — After replacing the MAP sensor or fixing a vacuum leak, this function should be performed to force the PCM to discard old adaptive fuel and idle strategies and relearn them with the correct sensor inputs.
• Ford IDS, FORScan: KOEO/KOER Self-Tests — To command the PCM to perform an on-demand check of all its sensor circuits. This can help identify underlying circuit faults (open, short) that might be the root cause of the performance code.

Wiring & Ground Locations

• Main Engine Ground Strap — Typically located on the transmission case, below the brake booster, connecting the engine/transaxle assembly to the chassis.. A loose, corroded, or broken main ground can cause a myriad of electrical issues, including erratic sensor data and floating voltages for the MAP sensor, leading to a P0106 code.
• G104 — A common ground point located on the right side of the engine compartment.. This ground serves various engine components, and a poor connection here can introduce electrical noise into sensor circuits, potentially affecting the MAP sensor reading.
• MAP Sensor Connector — On the MAP sensor itself, which is mounted to the intake manifold.. This 3-pin connector provides the sensor with its 5V reference, ground, and returns the signal to the PCM. A broken locking tab, corrosion, or loose pins can directly cause P0106, P0107, or P0108 codes.

Real Owner Repair Stories

• YouTube user on a Ford F-150 with 3.5L engine (2013 Ford F-150 3.5L EcoBoost) — Rough idle, lack of power, check engine light, wrench light, P0106 code, and lean codes.
  ❌ Tried (didn't work) Replaced all timing components (chains, phasers, etc.) based on history codes.
  ✅ What actually fixed it Replacing the MAP sensor on top of the intake manifold. The diagnostic giveaway was a KOEO test showing the MAP sensor reading 74 kPa while the BARO sensor read a correct 98 kPa. The new sensor read correctly at 97 kPa, and all symptoms were resolved.
• Ford F150 Forum user (2011 Ford F-150 3.5L EcoBoost, 115k miles) — Uneven running at wide-open throttle, then codes P0106, P0108, P0098 after changing the MAP sensor.
  ❌ Tried (didn't work) Replacing spark plugs and coil packs., Replacing the MAP sensor multiple times with different new parts.
  ✅ What actually fixed it The connector clip for the MAP sensor was broken, causing a poor electrical connection. After installing a new OEM (FoMoCo) sensor and ensuring the connector was secure, the codes cleared and the engine ran smoothly.

"I Checked Everything" — The Actual Cause

• In a well-documented case on a related 3.5L engine, the vehicle had a rough idle, lean codes, and a P0106. A smoke test would have come back clean because the issue was not a vacuum leak. The root cause was an electronically faulty MAP sensor that was providing an incorrect, but stable, low reading (74 kPa instead of the ambient 98 kPa). The PCM interpreted this as high vacuum (low load) and adjusted throttle and fuel incorrectly, causing the drivability issues. The fix was replacing the sensor itself.

OEM Part Supersession History

• AA5Z-9F479-C → AA5Z-9F479-E — Part revision or supplier change. The 'E' revision is listed for the similar 3.5L EcoBoost in the Taurus SHO.
  Heads up: Be cautious of part number AA5Z-9F479-D; this is a 3-Bar MAP sensor designed for modified, higher-boost engines and requires custom ECU tuning to function correctly. Installing it on a stock engine will cause incorrect readings and performance issues.

Model Year Variations Within This Range

• 2011-2019: The diagnosis and common causes for P0106 on the naturally aspirated 3.5L Cyclone V6 are consistent across this entire model range. The 2016 refresh was primarily cosmetic and did not significantly alter the engine management system, MAP sensor, or vacuum line configuration for this engine.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Internal Water Pump Failure 🔴 High — Commonly occurs between 80,000 and 150,000 miles. A lawsuit was filed over this issue, though it was dismissed.
• Power Transfer Unit (PTU) Overheating and Failure 🔴 High — Can occur at various mileages, often accelerated by lack of maintenance. The fluid is considered 'lifetime' by Ford but degrades due to heat from the nearby exhaust.
• Electronic Throttle Body (ETB) Malfunction 🟠 Medium — Common on 2011-2019 models, leading to extended warranty programs for certain years. (Ref: Extended Warranty Programs (not a formal recall))
• Cracked Exhaust Manifold / Carbon Monoxide Leak 🔴 High — A well-documented issue, particularly in Police Interceptor models, that led to recalls and investigations. (Ref: NHTSA Investigation EA16001, Recall 17V294000)
• A-Pillar Trim Detachment 🟡 Low — Common enough to warrant a recall across many model years. (Ref: Recall 19V435000)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, buying used parts is generally not recommended for the key components. However, if a larger assembly like the entire intake manifold is being replaced, using a low-mileage used unit can be cost-effective. Simple brackets or fasteners are also fine to source from a salvage yard.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For any used plastic or rubber parts like vacuum harnesses, inspect for brittleness, cracking, or heat stress.
• Ensure all connector locking tabs are intact and not broken.
• Verify the donor vehicle was not in a front-end collision that could have stressed plastic components.

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

• Manifold Absolute Pressure (MAP) Sensor: Owner and technician reports frequently cite aftermarket sensors being dead-on-arrival or failing within a short period. Using an OEM Motorcraft or a direct OEM supplier like Bosch is strongly recommended to avoid repeat repairs.

Aftermarket brands forum-validated for this vehicle:

• Bosch (often an OEM supplier for Ford)
• NTK/NGK
• Standard Motor Products (SMP)

Brands owners have reported issues with on this vehicle:

• Unnamed or 'white-box' sensors from online marketplaces should be avoided, as their quality control is often poor and can lead to wasted time and money.

Real Owner Stories

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

Related OBD-II Codes

• P0401 — Often appears alongside P0106 when vacuum lines or plastic tubing in the intake/EGR system fail or disintegrate.
• P2111 — Indicates the throttle actuator is stuck open; frequently occurs with P0106 when the Electronic Throttle Body is contaminated with carbon and oil sludge.
• P2112 — Indicates the throttle actuator is stuck closed; related to the same PCV-induced sludge buildup that causes P0106.
• P0107 — A companion MAP sensor circuit code that may trigger if the sensor's electrical connector is corroded or the 5-volt reference signal is lost.

Frequently Asked Questions