🧭 Diagnostic Flowchart 🎬 Helpful Videos 🛍️ Shop This Part

P2111 on 2007-2015 Mazda CX-9: Throttle Actuator Stuck Open Causes and Fixes

This code means the throttle body is stuck open, causing limp mode and poor performance. The most common fix is cleaning or replacing the electronic throttle body assembly. Cleaning is a temporary fix at best; replacement is usually required. The part can cost between $150 and $450.

22 minutes to read 2007-2015 Mazda CX-9

Most Likely Cause

Dirty or Sticking Throttle Body

Difficulty

2/5

Est. Time

1 hrs

DIY Doable?

✅ Yes

Shop Labor

$250 – $650

Parts Price

$150 – $450

⚠️ Drivable, but... — Driving is possible but not recommended. The vehicle will be in 'limp mode' with severely reduced engine power, making it difficult and unsafe to keep up with traffic. The failure can be intermittent at first but will likely become permanent, potentially leaving you stranded.

Key Takeaways

P2111 on a 2007-2015 Mazda CX-9 means the throttle body is stuck open, which will trigger a 'limp mode' and make the vehicle unsafe to drive in normal traffic.
Before spending money, the first step should always be to inspect and clean the throttle body, as carbon buildup is a very common cause.
If cleaning doesn't work, the entire throttle body assembly likely needs to be replaced. Be cautious with cheap remanufactured parts, as they may not be reliable.
After cleaning or replacing the throttle body, a 'relearn' procedure is often necessary for the engine to idle correctly.
This is a DIY-friendly repair for those with basic tools, with the most common fix being a simple cleaning or a bolt-off, bolt-on replacement of the throttle body.

The trouble code P2111 stands for 'Throttle Actuator Control System - Stuck Open'. On your Mazda CX-9, this means the Powertrain Control Module (PCM) has detected that the throttle plate inside the throttle body is open more than it should be. The electronic throttle control system uses a motor to open and close this plate, controlling how much air enters the engine. When the PCM commands the throttle to close, but sensors indicate it's still open, it triggers this code and puts the vehicle into a fail-safe 'limp mode' to prevent unintended acceleration.

What's Unique About the 2007-2015 Mazda CX-9

The first-generation Mazda CX-9 uses a 3.7L V6 engine (a Ford Cyclone engine) with an electronic throttle body known to be susceptible to carbon and oil sludge buildup. This accumulation can cause the throttle plate to become sticky or physically obstructed, leading directly to the P2111 code. While the issue is common across many 'drive-by-wire' systems, the specific throttle body used on this platform and its Ford/Lincoln siblings is known for a high failure rate of the internal electronics, often making cleaning an ineffective long-term solution.

Symptoms You May Notice

Check Engine Light is on
Wrench light (throttle control malfunction indicator) is on
Vehicle enters 'limp mode' with drastically reduced power
Poor or no acceleration
Unstable or high idle
In some cases, the engine may stall or fail to start
Engine RPM limited, will not rev up

⚠️ Don't Waste Money on the Wrong Fix

Replacing the accelerator pedal position (APP) sensor. While the APP sensor is part of the overall throttle control system, a failure there typically sets different codes. The P2111 code specifically points to a discrepancy at the throttle body itself.

Most Likely Causes

Dirty or Sticking Throttle Body 🔴 High Probability → Shop Fuel Injection Throttle Body The MZI 3.7L V6 engine's PCV (Positive Crankcase Ventilation) system can introduce oil vapor and fuel into the intake, which bakes onto the throttle body over time, causing a sticky residue that impedes plate movement.
How to confirm: Remove the air intake hose connected to the throttle body. Visually inspect the throttle plate and bore for black carbon/oil buildup. Gently push the plate with your finger (with the engine off); it should move smoothly and snap back without sticking. If it feels gritty or hangs up, it needs cleaning.
Typical fix: Clean the throttle body bore and plate with a dedicated throttle body cleaner and a soft cloth or brush. A throttle relearn procedure is required after cleaning. While this may work, it is often a temporary fix if the internal electronics are the root cause.
Est. part cost: $5-$15
Failed Throttle Body Assembly Very High Probability → Shop Fuel Injection Throttle Body This is the most common cause. The internal electric motor or position sensor within the throttle body assembly fails electronically. This is a well-documented, widespread issue on the Ford Cyclone engine family, including the 3.7L in the CX-9. Remanufactured units from some brands have a high rate of repeat failure.
How to confirm: If cleaning the throttle body does not resolve the issue, and the wiring is confirmed to be good, the assembly itself is faulty. A diagnostic scan tool can command the throttle open and closed to observe its response. A failure to respond correctly confirms a bad throttle body. Restarting the car may temporarily clear the fault, but it will return.
Typical fix: Replace the entire throttle body assembly. It is highly recommended to use an OEM or high-quality aftermarket part (e.g., Hitachi, Bosch). A new gasket should be used.
Est. part cost: $150-$450
Wiring or Connector Issue ⚪ Low Probability Vibrations and heat in the engine bay can cause wires to chafe or the connector at the throttle body to become loose or corroded over time.
How to confirm: Visually inspect the wiring harness leading to the throttle body for any signs of damage, melting, or chafing. Unplug the connector and check for corrosion, moisture, or bent pins.
Typical fix: Repair the damaged section of wire or clean/replace the connector pigtail.
Est. part cost: $10-$50

Rare But Worth Checking

Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. Before condemning the PCM, all other possibilities (throttle body, wiring) must be exhaustively ruled out. A forum user on Mazdas247 reported suspecting a bad ECM after replacing the throttle body five times with remanufactured units, highlighting the importance of using quality parts before suspecting the PCM.
Low Battery Voltage: While less common, a failing battery or alternator can cause low system voltage, which may trigger various electronic-related codes, including P2111. It is a good practice to test the battery and charging system to rule this out.

Diagnosis Steps

Read the codes with an OBD-II scanner and confirm P2111 is present. Note any other codes, as they provide critical context.
Turn the vehicle off. Remove the air intake ducting from the throttle body.
Visually inspect the throttle plate and bore for heavy carbon buildup.
With your finger, gently push the throttle plate open. It should move smoothly and snap shut when released. If it's sticky or gritty, it needs cleaning.
If dirty, clean the throttle body thoroughly using a dedicated throttle body cleaner and a soft rag or brush. Do not spray harsh chemicals directly on the electrical connector.
Inspect the electrical connector and wiring harness at the throttle body for any signs of damage, corrosion, or loose connections.
After cleaning or replacement, clear the codes and perform a throttle body relearn procedure. A common procedure for Fords/Mazdas is to turn the ignition to 'ON' (engine off), slowly press the accelerator pedal to the floor and slowly release it, then turn the ignition off. Start the engine and let it idle to confirm the fix.
If the code returns immediately after cleaning and a relearn, the throttle body assembly itself has almost certainly failed electronically and requires replacement.

Parts You'll Likely Need

Electronic Throttle Body Assembly (OEM #CA38-13-640) — This is the complete unit that fails, either due to internal motor/sensor failure or because it's too contaminated to be cleaned effectively. It is the primary fix for a persistent P2111 code.
Trusted brands: Mazda (OEM), Hitachi, Bosch, Cardone (Note: some forum users report repeated failures with remanufactured units)
OEM price range: $350-$450
Aftermarket price range: $150-$300
Throttle Body Gasket (OEM #L3G2-13-655) — The gasket should always be replaced when the throttle body is removed to ensure there are no vacuum leaks.
Trusted brands: Fel-Pro, Mahle, Mazda (OEM)
OEM price range: $10-$20
Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

P2104 — This code indicates 'Throttle Actuator Control System - Forced Idle'. The PCM sets this code to force the engine to idle as a safety measure when it detects a critical fault like P2111.
P2110 — This code means 'Throttle Actuator Control System - Forced Limited RPM'. It's another fail-safe mode triggered by the PCM in response to the throttle body fault.
P2112 — This is the opposite of P2111, indicating 'Throttle Actuator Control System - Stuck Closed'. It can sometimes appear alongside P2111 if the throttle body is failing intermittently and getting stuck in both directions.

Technical Service Bulletins (TSBs) & Recalls

Ford TSB 10-21-6: While for Ford/Lincoln models, this TSB is highly relevant as it covers the same 3.7L engine and P2111/P2112 codes. It recommends replacing the throttle body on vehicles built within a specific date range (March to August 2010), confirming a known hardware issue.
Mazda TSB 01-007/13: This TSB for the Mazda Tribute also mentions P2111 as a possible related code to P2135 (Throttle Position Sensor Correlation) and recommends throttle body replacement, showing a pattern of similar fixes across Mazda platforms.
Bulletin #01-007-13-2767: This manufacturer bulletin notes that a Check Engine Light or Wrench Light may be accompanied by DTC P2135, and that P2111 (Throttle Actuator Control System - Stuck Open) may also be present.

Mechanic-Grade Diagnostic Values

Throttle Position Sensor 1 (TP1) and 2 (TP2) Voltage — expected: Voltage should change smoothly as the accelerator pedal is operated. Specific voltage at idle vs. wide-open throttle varies, but one sensor (TP1) typically sweeps from low to high voltage (~0.5V to ~4.5V) while the other (TP2) sweeps from high to low (~4.5V to ~0.5V) as a cross-check.. Failure: No change in voltage, erratic jumps, or voltage not matching the commanded throttle position indicates a fault.
Continuity Check between Throttle Body and PCM — expected: Continuity (near 0 ohms) should exist between the corresponding pins.. Failure: No continuity (OL) indicates an open circuit in the harness. Continuity to power or ground on a signal wire indicates a short circuit.
Throttle Motor Resistance (for 2007 3.5L engine) — expected: 1 - 900 ohms between terminals A and B.. Failure: Resistance outside this range indicates a faulty throttle motor.

Scan Tool Commands That Help

Mazda M-MDS (or equivalent like FORScan): PID Data Monitoring (TP1, TP2) — Use this to watch the live voltage output of both throttle position sensors simultaneously while operating the pedal or running an actuator test. This can reveal glitches or a sensor that is not responding.
Professional Scan Tool (Mazda IDS, Autel, Snap-on, etc.): Throttle Actuator Test (Bidirectional Control) — This command allows the technician to directly order the throttle plate to open and close. If the plate fails to move as commanded while sensor data is monitored, it confirms a failure in the throttle body motor or a mechanical jam.
Factory or Advanced Aftermarket Scan Tool: Throttle Body Relearn / Reset Adaptive Values — Use this after replacing the throttle body, especially if the manual relearn procedure fails. In some cases, the PCM's learned adaptation values are too far out of range for a manual reset to work, and a scan tool is required to force the reset.

Wiring & Ground Locations

Throttle Body Connector Pins to PCM — The throttle body is on the top rear of the engine. The PCM is located elsewhere in the engine bay. Specific pin-to-pin checks are required.. A service manual for the 2008 3.7L specifies checking continuity from Throttle Body terminal C to PCM terminal 2AD, D to 2D, E to 2AH, and F to 2Z. A break in any of these wires will cause throttle control failure and trigger codes.
G11 — Behind the left side of the dashboard.. This is a major ground point for interior and dash components. While not directly for the throttle body, a poor ground here can cause a host of strange electrical issues and potentially affect modules that communicate with the PCM.
G13 — At the left 'C' pillar.. This is a body ground point. Poor grounding can lead to floating voltages and unpredictable behavior from electronic modules, which can indirectly contribute to control system faults.

Real Owner Repair Stories

Mazdas247 Forum User 'EMT' (2008 Mazda CX-9) — Check Engine Light and Wrench Light on, vehicle enters limp mode. Codes P2101, P2104, P2110, P2111, and P2112 all present.
❌ Tried (didn't work) Replacing the throttle body with a Cardone remanufactured unit. The problem would be fixed for a few weeks to a month, then return., This cycle was repeated FIVE times with different remanufactured throttle bodies.
✅ What actually fixed it The user did not post a final resolution, but the critical lesson was the repeated failure of remanufactured throttle bodies. The strong implication is that only a new OEM or high-quality OEM-equivalent (Hitachi, Bosch) part is a reliable fix, or that a deeper issue like a faulty PCM was destroying the replacement parts. The user suspected the PCM might be the ultimate cause.
NHTSA ODI #10567410 — An owner of a related Mazda model reported that the vehicle became unresponsive while the engine was still running, requiring a shutdown and restart in the middle of the road. A service technician found stored code P2111 for the throttle actuator control system being stuck open.

OEM Part Supersession History

CA38-13-640 → CA01-13-640B, TK21-13-640 — Standard part revision and updates by the manufacturer.
Heads up: While the 3.7L engine is a Ford design, throttle bodies from other Ford models (like the Mustang or Fusion) are not directly compatible due to differences in electronic programming and connector orientation.

Model Year Variations Within This Range

2007 vs 2008-2015: The 2007 model year used a 3.5L V6 engine. From 2008 onwards, the CX-9 used the 3.7L V6. While both are Ford Cyclone family engines, the throttle body and associated part numbers may differ. This guide focuses on the 3.7L V6.
2010 & 2013: The CX-9 received facelifts for the 2010 and 2013 model years, primarily affecting aesthetics and interior features. The core powertrain, including the 3.7L engine and electronic throttle body, remained mechanically unchanged, so the P2111 fault applies consistently across the 2008-2015 range.

Diagnostic Flowchart

The P2111 code indicates the Throttle Actuator Control (TAC) system is stuck open. On the Mazda MZI 3.7L, this is frequently caused by carbon buildup or electronic failure of the Ford-sourced Cyclone engine throttle body.

Inspect the electrical connector and wiring harness at the throttle body. Are there signs of corrosion, bent pins, or oil contamination?

→ Repair the wiring or replace the pigtail connector. Oil contamination may indicate a PCV issue or a leaking valve cover gasket dripping onto the harness.

Remove the air intake duct. Manually push the throttle plate with your finger (engine off). Does it move smoothly and snap back, or is there sticky black residue?

Clean the bore and plate with dedicated throttle body cleaner. Perform the Mazda relearn (Ignition ON, slowly floor/release accelerator, then start). Does the code return?

→ Fix confirmed. Note: The 3.7L PCV system often causes this buildup; check the PCV valve to prevent recurrence.

Using a scan tool, command the throttle plate to various positions. Does the 'Throttle Position Actual' match the 'Desired' command?

→ The internal actuator motor has failed. Replace the throttle body assembly. This is a common failure on the Cyclone 3.7L engine family shared with the Ford Edge.

Does the vehicle enter 'Limp Mode' only after the engine is fully warmed up?

→ Heat-soak is causing an intermittent failure in the internal TPS sensor. Replace the throttle body assembly and install a new gasket.

→ Perform a pin-out test on the PCM to throttle body harness to check for high resistance or a failing PCM driver.

Using a scan tool, command the throttle plate to various positions. Does the 'Throttle Position Actual' match the 'Desired' command?

→ The internal actuator motor has failed. Replace the throttle body assembly. This is a common failure on the Cyclone 3.7L engine family shared with the Ford Edge.

Does the vehicle enter 'Limp Mode' only after the engine is fully warmed up?

→ Heat-soak is causing an intermittent failure in the internal TPS sensor. Replace the throttle body assembly and install a new gasket.

→ Perform a pin-out test on the PCM to throttle body harness to check for high resistance or a failing PCM driver.

Is the vehicle a 2010-2011 model or built between March and August 2010?

→ This aligns with Ford TSB 10-21-6 and Mazda TSB 01-007/13. These models have a high rate of internal electronic motor failure. Skip cleaning and replace the throttle body assembly with a high-quality OEM or Hitachi unit.