P2119 on 2014-2018 GMC Yukon: Throttle Body Causes and Fixes

What's Unique About the 2014-2018 Gmc YUKON

For this generation of GMC Yukon and its platform mates, P2119 is a well-documented issue, particularly on higher-mileage vehicles. As stated in GM's Technical Service Bulletin (TSB) #PIP4578B, carbon buildup inside the throttle body is a primary cause. Over time, the engine's computer learns to open the throttle plate wider to compensate for this buildup; eventually, it can no longer adjust, triggering the P2119 code and the 'Reduced Engine Power' message.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Reduced Engine Power" message on the dashboard
• Check Engine Light is on
• Sluggish or delayed acceleration
• Irregular, high, or low idle speed
• Vehicle may stall, especially at idle
• Poor or harsh transmission shifting
• Hesitation when accelerating

Most Likely Causes

1. Dirty Throttle Body 🔴 High Probability → Shop Fuel Injection Throttle Body As documented in TSB #PIP4578B, carbon deposits from the PCV system accumulate around the throttle plate over time, especially on high-mileage engines. This physically restricts the plate's movement, causing a mismatch between the commanded and actual position that the PCM flags as a P2119 fault.
   How to confirm: Remove the air intake duct from the throttle body and visually inspect the throttle bore and plate for a black, sooty carbon layer. The buildup is often heaviest on the back side of the plate and where the plate seats in the bore at idle.
   Typical fix: Thoroughly clean the throttle body bore and plate with a dedicated throttle body cleaner and a soft brush or lint-free rag. 🎬 Watch: How to clean a throttle body on your GM truck. After cleaning, an 'Idle Learn Reset' procedure must be performed with a capable scan tool to reset the learned idle values.
   Est. part cost: $10-$25 for cleaner and a gasket.
2. Failed Throttle Body Assembly 🟡 Medium Probability → Shop Fuel Injection Throttle Body The internal electronic motor or the dual throttle position sensors (TPS) within the assembly can fail. Forum users and mechanics strongly recommend using an OEM ACDelco replacement, as some aftermarket throttle bodies have been reported to fail prematurely or cause immediate issues due to different internal electronics and build quality.
   How to confirm: If cleaning the throttle body and performing an idle relearn does not resolve the code, and the wiring is confirmed to be good, the throttle body assembly itself is the likely culprit. A scan tool can monitor the dual TPS sensor voltages; erratic or non-linear readings during throttle operation point to a bad sensor.
   Typical fix: Replace the entire throttle body assembly. 🎬 See this walkthrough for diagnosing reduced power mode and throttle codes. An idle relearn procedure is required after installation.
   Est. part cost: $150-$530
3. Wiring or Connector Issue ⚪ Low Probability The wiring harness connector at the throttle body can develop corrosion, loose pins, or chafed wires, interrupting the signal between the PCM and the throttle body. The harness is subject to engine heat and vibration, which can degrade it over time.
   How to confirm: Inspect the throttle body connector for corrosion, bent pins, or damaged wires. Wiggle the harness while the engine is running to see if it affects idle. Check for continuity and proper voltage on the power, ground, and two TPS signal wires according to the vehicle's service manual. In some cases, a wire can have an internal break or high resistance that only shows up under load.
   Typical fix: Repair the damaged section of the wiring harness or replace the connector pigtail. Clean any corrosion from the connector pins. In a documented case, a technician bypassed a faulty signal wire by running a new wire directly from the ECM to the throttle body connector.
   Est. part cost: $15-$50 for a new connector pigtail.

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is very rare. Before condemning the PCM, all other possibilities, especially the throttle body, wiring, and ground connections, must be exhaustively ruled out. A PCM failure usually presents with multiple other unrelated codes. In some cases, a PCM software update may be available to address throttle control logic issues.
• Low Battery Voltage: The electronic throttle control system requires a stable voltage supply. A weak or failing battery or a faulty alternator can cause low voltage conditions (below 12.4V), leading to erratic throttle actuator performance and triggering a P2119 code.

Diagnosis Steps

1. Scan the PCM for P2119 and any other stored codes. Note all codes present and review freeze frame data.
2. Turn the ignition off and disconnect the negative battery terminal for safety.
3. Remove the air intake tube connected to the throttle body.
4. Visually inspect the throttle body plate and bore for heavy carbon buildup. Pay close attention to the edges of the plate and the bore where it seats.
5. If carbon is present, clean it thoroughly using dedicated throttle body cleaner and a soft, lint-free cloth or soft brush. Do not use abrasive tools. To open the plate for cleaning, have a helper turn the ignition to 'ON' (engine off) and press the accelerator pedal. Do not force the plate by hand.
6. Inspect the electrical connector at the throttle body for any signs of corrosion, moisture, or damaged pins/wires. Ensure it is seated securely.
7. If cleaning was performed, reconnect everything, including a new throttle body gasket if required. Reconnect the battery.
8. Perform the 'Idle Learn Reset' procedure. The official method requires a scan tool (like a Tech 2 or GDS2) to access the 'Module Set Up' or 'Special Functions' menu. A manual procedure exists but is often less effective: Idle in PARK for 3 mins, turn ignition OFF for 60 seconds, then idle in PARK for another 3 mins. A drive cycle with speeds over 44 mph may be needed 🎬 Watch: How to manually reset and relearn your GM throttle body. if idle is still high.
9. If the code returns after cleaning and a successful relearn, test the wiring between the PCM and the throttle body for proper voltage, ground, and signal integrity using a multimeter and wiring diagram.
10. If wiring is confirmed to be good, the throttle body assembly is likely faulty and requires replacement.

Parts You'll Likely Need

• Throttle Body Assembly (OEM #12678224) — This is the most common fix if cleaning the original unit does not resolve the issue. The internal motor or sensors fail, requiring a full replacement. Part number 12678224 has been superseded by 12740725. Another common number for these trucks is 12679524. Always verify the correct part number with the vehicle's VIN.
  Trusted brands: ACDelco (OEM), Hitachi, Dorman
  OEM price range: $170-$350
  Aftermarket price range: $150-$260
• Throttle Body Cleaner — Required for the most common and least expensive repair attempt: cleaning carbon buildup from the throttle plate and bore.
  Trusted brands: CRC, Berryman, ACDelco Top Engine Cleaner
  OEM price range: $10-$15
  Aftermarket price range: $8-$12

Related Codes That Often Appear With This One

• P1516 — This is a GM-specific code for 'Throttle Actuator Control (TAC) Module Position Performance' and is often set with P2119 as they both relate to the PCM's inability to control the throttle plate.
• P2101 — This code for 'Throttle Actuator Control Motor Circuit Range/Performance' points directly to an issue with the motor that moves the throttle plate, often caused by the same binding (carbon) or electrical issues that trigger P2119.
• P2176 — This code means 'Throttle Actuator Control System - Idle Position Not Learned'. It frequently appears after a throttle body has been cleaned or replaced but the mandatory idle relearn procedure was not performed correctly or was unsuccessful.
• P0068 — Indicates a mismatch between the Mass Airflow (MAF) sensor and the throttle position sensor. A sticking throttle plate can cause this correlation error.
• P0121 — This code for 'Throttle/Pedal Position Sensor 'A' Circuit Range/Performance' can be triggered by the same carbon buildup or throttle body failure.
• P2135 — This code for 'Throttle/Pedal Position Sensor/Switch 'A'/'B' Voltage Correlation' points to a disagreement between the two internal throttle position sensors. It often accompanies P2119 when the throttle body assembly is failing internally.

Technical Service Bulletins (TSBs) & Recalls

• PIP4578B: Addresses idle surge, reduced engine power, and multiple DTCs including P2119, P0068, P0121, P1516, P2101, and P2176 on high-mileage vehicles due to carbon buildup in the throttle body. Recommends cleaning and performing an idle learn reset with a Tech 2/GDS scan tool.

Platform-Specific Known Issues

• As per TSB #PIP4578B, these vehicles are known to accumulate carbon in the throttle body, leading to P2119 and Reduced Power Mode, especially at high mileage.
• Failure to perform the 'Idle Learn Reset' with a scan tool after cleaning or replacing the throttle body is a common cause for the problem to persist or for new codes like P2176 to appear. Some owners on forums report driving for over 100 miles without the computer successfully relearning on its own, eventually requiring a scan tool reset.
• Some owners on the 'Tahoe Yukon Forum' have reported that even after cleaning the throttle body and performing the relearn procedure, a high idle or other issues persist, sometimes pointing to a faulty new part or an underlying issue that was masked by the carbon buildup.

Mechanic-Grade Diagnostic Values

• Throttle Position Sensor (TPS) 1 & 2 Voltage — expected: Smoothly sweep from approximately 0.5V to 4.5V as the throttle plate is opened and closed. The two sensors should have opposing sweeps (one increases while the other decreases).. Failure: Any glitches, spikes, or flat spots in the voltage reading indicate a failing sensor within the throttle body assembly.
• Throttle Actuator Power Supply Voltage — expected: 11.5V – 13.5V with the engine running.. Failure: Persistent voltage below 11.5V suggests a problem with the battery, alternator, or a poor ground connection, which can cause false P2119 codes.
• Throttle Body Connector Pinout (Typical 8-Pin) — expected: Pin E (LT BLU/BLK): 5V Reference; Pin F (PPL): TP Sensor 2 Signal; Pin G (DK GRN): TP Sensor 1 Signal; Pin H (GRY): 5V Reference.. Failure: Incorrect or missing voltages at these pins point to a wiring or PCM issue.
• Signal Wire Continuity — expected: Less than or equal to 0.5 Ω.. Failure: Higher resistance indicates a break or corrosion in the wire between the throttle body and the PCM.

Scan Tool Commands That Help

• GDS2 / Tech2 or equivalent professional scan tool: Idle Learn Reset / Reset ECM Learned Values — This is mandatory after cleaning or replacing the throttle body. It erases the old learned values that compensated for carbon buildup, preventing high idle or stalling with the new/clean part.
• Bi-directional scan tool: Throttle Actuator Test / Throttle Sweep — Used to command the throttle plate to open and close. This helps determine if a lack of movement is due to a failed actuator motor or a physical obstruction (like carbon) without having to remove the part first.

Wiring & Ground Locations

• Throttle Body Connector (X125) — Directly on the electronic throttle body assembly at the front of the intake manifold.. This is the primary connection point for all power, ground, and signal wires for the throttle actuator motor and position sensors. Corrosion or broken wires here (especially the purple or dark green signal wires) are a known cause of P2119.
• G103 / G104 — These are key engine-to-chassis grounds. G103 is often located on the front of the passenger-side cylinder head. G104 is a ground strap from the rear of the driver-side cylinder head to the firewall.. A poor connection at these ground points can cause electrical noise and voltage drops throughout the engine management system, leading to incorrect sensor readings and false throttle-related codes like P2119.

Real Owner Repair Stories

• Hayes Mobile Auto Repair YouTube Channel (GM Truck with 'Reduced Engine Power' mode (similar system to Yukon)) — Vehicle went into 'Reduced Engine Power' mode, high idle up to 3000 RPM, and set codes P2119, P0122, and P0504.
  ❌ Tried (didn't work) Replacing the throttle body assembly.
  ✅ What actually fixed it The technician found a broken purple wire inside the wiring harness loom near the throttle body connector. Repairing the broken wire and replacing the connector pigtail resolved the issue. An 'idle relearn reset' with a scan tool was required afterward to correct the high idle.

"I Checked Everything" — The Actual Cause

• In cases where P2119 persists after cleaning or replacing the throttle body, the root cause is often electrical, not a vacuum leak that a smoke test would find. A documented repair shows that a new throttle body did not fix the code, but a detailed inspection of the wiring harness revealed a broken signal wire near the connector. The fault was internal to the harness and not visually obvious, leading previous mechanics to misdiagnose the issue as a faulty component.

When the Usual Fixes Don't Work

• While a dirty or failed throttle body is the most frequent cause of P2119, it is not the only cause. There are confirmed cases where replacing the throttle body did not fix the problem. In one such instance, the actual fault was a broken signal wire within the wiring harness near the throttle body connector. This highlights that if cleaning or replacing the throttle body does not resolve the code, a thorough inspection of the wiring harness for continuity and damage is a critical next step before considering a rare PCM failure.

OEM Part Supersession History

• 12678224 → 12740725 — Standard part revision by the manufacturer.