P2100 on 2010-2012 Mitsubishi Outlander: Causes and Fixes for Throttle Control Issues

What's Unique About the 2010-2012 Mitsubishi OUTLANDER

The 2010-2012 Outlander is uniquely susceptible to this code in cold climates. Mitsubishi issued a Technical Service Bulletin (TSB-13-13-005) acknowledging that residual moisture from the EGR system can freeze 🎬 See how to remove and clean the throttle and EGR. the Electronic Throttle Valve (ETV) at temperatures around 23°F (-5°C). This icing condition prevents the throttle plate from moving, which the ECM interprets as an open circuit in the control motor, triggering the P2100 code and often causing hard starting or a failure to start. The official fix is a dealer-installed software update for the ECM that changes the EGR activation temperature to prevent the freezing from occurring.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Reduced engine power (Limp Mode)
• Engine hesitation or stalling
• Hard to start, especially in cold weather
• Unresponsive or sluggish accelerator pedal
• Engine will not accelerate above 20-30 MPH
• Rough or erratic idle

Most Likely Causes

1. Frozen/Sticking Electronic Throttle Valve (ETV) 🔴 High Probability As per Mitsubishi TSB-13-13-005, moisture from the EGR system can freeze the throttle plate in sub-freezing temperatures (around 23°F / -5°C), causing a P2100 code. This is a well-documented factory issue.
   How to confirm: The issue primarily occurs during cold starts in winter. If the code appears consistently in these conditions but not in warmer weather, this is the likely cause. Freeze frame data from a scan tool should show a low ambient temperature when the code was set.
   Typical fix: Mitsubishi released updated ECM software to change the EGR activation temperature and prevent freezing. A dealer can perform this reprogram, which takes approximately 0.3 labor hours under warranty. If the throttle body is damaged from being forced open while frozen, it may still need replacement.
   Est. part cost: $0 (if only reprogram is needed, though dealer labor charges will apply if out of warranty)
2. Failed Throttle Body Assembly 🟡 Medium Probability → Shop Fuel Injection Throttle Body The internal motor (Throttle Actuator Control Motor) or position sensor can fail electrically over time. This is a common failure point for electronic throttle bodies in general across many vehicles.
   How to confirm: After confirming the wiring is intact, test the resistance of the motor terminals on the throttle body (ETV+ and ETV-). According to service data, it should be between 0.3 and 100 ohms at 68°F (20°C). If it's outside this range (e.g., an open circuit), the motor has failed.
   Typical fix: Replace the entire throttle body assembly. The actuator motor is integrated into the assembly and not sold separately. After replacement, a throttle relearn procedure is required.
   Est. part cost: $150-$450 (Aftermarket), $850+ (OEM)
3. Wiring or Connector Damage ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness and the 6-pin connector at the throttle body for any signs of chafing, corrosion, or loose pins. Perform a continuity test on the ETV+ and ETV- wires between the ECM and the throttle body connector to check for an open circuit.
   Typical fix: Repair the damaged section of the wiring harness or replace the corroded connector.
   Est. part cost: $10-$100

Rare But Worth Checking

• Failed Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is the least likely cause. The ECM should only be considered after all other possibilities, including the TSB, the throttle body itself, and all related wiring, have been definitively ruled out.
• Failed Throttle Actuator Relay: Some forum discussions mention a throttle actuator relay that could fail and cause an open circuit. This should be investigated before condemning the throttle body or ECM.

Diagnosis Steps

1. Read the freeze frame data to see the conditions (especially ambient temperature) when the code was set. If it was around or below 23°F / -5°C, suspect the TSB issue.
2. Check for the presence of Mitsubishi TSB-13-13-005. If the symptoms match (cold weather starts), contact a dealer about the ECM reprogram. The TSB specifies this is the first step if no other cause is found.
3. Visually inspect the wiring harness and the 6-pin connector at the throttle body for damage, corrosion, or loose connections.
4. If wiring appears okay, disconnect the throttle body and measure the resistance between the two motor terminals (ETV+ and ETV-). A normal reading is between 0.3 and 100 ohms at room temperature. If the reading is infinite (open), the throttle body has failed.
5. If the resistance is out of spec, the throttle body assembly is faulty and needs to be replaced.
6. If resistance is normal, perform a continuity check on the wiring between the throttle body connector and the ECM connector to rule out an open circuit in the harness.
7. If both the throttle body and wiring test good, the fault may lie with the throttle actuator relay or, rarely, the ECM itself.
8. After any replacement of the throttle body, perform a throttle relearn procedure.

Parts You'll Likely Need

• Throttle Body Assembly (OEM #1450A101) — This assembly contains the electronic throttle motor that fails or freezes, causing code P2100. It is replaced as a single unit. This part number is applicable to the 2.4L engine.
  Trusted brands: Mitsubishi (OEM), Hitachi, Bosch, Standard Motor Products
  OEM price range: $860 - $1200
  Aftermarket price range: $150 - $300

Related Codes That Often Appear With This One

• P0638 — This code for 'Throttle Actuator Control Range/Performance' often appears with P2100 because if the circuit is open (P2100), the throttle plate's position will not match what the ECM expects, causing a range/performance error.
• P2101 — This code, 'Throttle Actuator 'A' Control Motor Circuit Range/Performance', is very similar to P0638 and can be triggered for the same reasons when P2100 is present.
• P0657 — This code for 'Throttle Actuator Control Motor Relay Circuit Malfunction' points to an issue with the relay or its circuit, which provides power to the throttle actuator system. A fault here will cut power, leading to P2100.

Technical Service Bulletins (TSBs) & Recalls

• TSB-13-13-005: Addresses ECM reprogramming for false MIL illumination with P2100 or hard starting in cold weather due to a frozen Electronic Throttle Valve (ETV).

Platform-Specific Known Issues

• A known issue documented in TSB-13-13-005 describes the throttle valve freezing due to moisture from the EGR system in cold weather (approx. 23°F / -5°C), leading to a 'false' P2100 code. The official fix is an ECM software update.
• After replacing the throttle body, a 'throttle relearn' procedure is mandatory. A common method involves disconnecting the battery for a minute, reconnecting it, turning the ignition to 'ON' (without starting) for 1-2 minutes, then starting the engine and letting it idle for 10-15 minutes.
🎬 Watch: A quick guide to resetting your throttle position sensor.

Mechanic-Grade Diagnostic Values

• Throttle Actuator Control Motor Resistance — expected: 0.3 to 100 Ohms at 20°C (68°F). Failure: Infinite resistance (open circuit) or a reading outside the specified range.
• Throttle Actuator Control Motor Relay Continuity — expected: Continuity (≤ 2 Ω) between terminals 3 and 4 when battery voltage is applied to terminals 1 and 2.. Failure: No continuity when energized, or continuity when de-energized.
• Voltage at Throttle Actuator Control Motor Relay Harness Connector (A-18X/A-21X) — expected: Battery positive voltage at terminal 2 (from MFI relay) and terminal 4 (from battery) with ignition ON.. Failure: Voltage below battery voltage indicates an open/short in the power supply wiring or a faulty MFI relay.
• DTC Set Condition Voltage Differential — expected: The difference between target TPS voltage and actual TPS voltage should be less than 0.1V.. Failure: A difference greater than 0.1V while the ECM commands 100% motor duty indicates the throttle is stuck, triggering P2100.

Scan Tool Commands That Help

• Mitsubishi MUT-III (MB991958): Actuator Test — To command the throttle actuator motor to move without engine operation, verifying its mechanical and electrical function independently of other systems.
• Mitsubishi MUT-III (MB991958): ECU Reprogramming — Required to perform the fix outlined in TSB-13-13-005, which involves updating the ECM software to prevent throttle body icing.

Wiring & Ground Locations

• Throttle Actuator Control Motor Relay — Located in the engine room relay box, on the left side of the engine compartment.. This relay provides operating voltage to the electronic throttle control system. Its failure or a lack of power/ground to it will cause P2100 and related power supply codes like P0657.
• ECM (Engine Control Module) — Located in the left rear corner of the engine compartment.. The ECM controls the throttle actuator motor via the ETV+ and ETV- circuits and uses dedicated internal grounds for this function.
• Ground G12 / G13 / G15 — Various points on the left side of the engine compartment, near the front and side.. These are primary engine compartment grounds. A loose or corroded connection at these points can cause a variety of electrical issues, including intermittent faults in the throttle control system.
• Throttle Body Connector — 6-pin connector directly on the throttle body assembly. May be labeled B-10, B-06, or C-126 depending on the specific wiring diagram.. This is the primary connection point for testing the throttle motor (ETV+/ETV-) and throttle position sensors. Corrosion or damage here is a direct cause of an open circuit.

Real Owner Repair Stories

• YouTube channel 'mechanic's life' (Mitsubishi Outlander (2nd Gen, similar to 2010-2012)) — Engine running very rough ('like a dog'), hunting idle, and DTC P0657 (Throttle Actuator Control Motor Relay Circuit) was present.
  ❌ Tried (didn't work) The owner had replaced the battery, after which the problem started.
  ✅ What actually fixed it The mechanic diagnosed a lack of power at the ETV (Electronic Throttle Valve) relay. The relay itself tested good. The root cause was a missing fuse in the engine bay fuse box that supplied power to the relay's switched circuit. After installing the correct fuse and performing a throttle idle relearn procedure, the idle returned to normal and the code was resolved.

When the Usual Fixes Don't Work

• While the TSB for a frozen throttle body and a failed throttle body assembly are the most common causes, a significant counter-example exists where the root cause is a simple power supply issue. In one documented case, a missing fuse for the throttle actuator relay caused code P0657 and resulted in P2100 symptoms. Replacing the throttle body would not have fixed this issue. This highlights the importance of checking for power at the throttle actuator relay before condemning the more expensive throttle body or ECM, especially if a relay circuit code like P0657 is also present.

OEM Part Supersession History

• 1450A101 → 1450A195 — Likely an updated or revised part from the manufacturer, though specific reasons are not documented in public sources.
  Heads up: 1450A195 is listed as a direct replacement for 1450A101 for the specified Outlander models.

Model Year Variations Within This Range

• 2010-2012: The 2010 model year marked a significant cosmetic facelift for the Outlander, introducing the 'Jet Fighter' grille. However, the 2.4L 4B12 powertrain and related electronic throttle control system remained consistent through 2012, making the diagnosis for P2100 the same across this range.