P2112
Actuator Control System - Stuck ClosedP2112 is a generic OBD-II powertrain diagnostic trouble code: Actuator Control System - Stuck Closed. It is logged by the engine control unit when the scr/adblue monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P2112 means
P2112 is stored when the PCM determines that the electronic throttle plate cannot open from a closed (or nearly closed) position, despite the PCM commanding it to open. In a drive-by-wire throttle system, the PCM sends a control signal to the throttle actuator motor to open the plate in response to accelerator pedal input. When the position sensors report that the plate has not moved to the commanded angle, P2112 is triggered.
A throttle plate stuck in the closed position starves the engine of air, causing severe power loss, rough idling, stalling, and in extreme cases a no-start condition. The PCM will enter fail-safe mode, restricting engine output to protect the drivetrain and alert the driver. Carbon buildup around the throttle bore is the leading mechanical cause, especially on high-mileage vehicles or those using oil-catch-can systems improperly routed. Actuator motor failure, a broken drive gear inside the throttle body, or a seized shaft are other mechanical culprits.
On the electrical side, an open or short in the motor drive circuit, corroded connector terminals, or a faulty TPS that misreports plate position can all produce this code without any mechanical fault. Because the PCM relies on the TPS voltage to confirm plate movement, a drifted or failed sensor is a common finding even when the throttle body itself is serviceable.
Diagnosis starts with a scan tool to confirm the fault and observe live throttle-angle data. Manual inspection and cleaning of the throttle body plate and bore is a low-cost first step. Electrical testing of the actuator motor, its drive circuit, and the TPS follow if cleaning does not resolve the fault.
Common causes
Most-frequently reported root causes when P2112 is logged.
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1
Carbon or varnish buildup preventing the throttle plate from opening
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2
Failed or seized throttle actuator motor
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3
Broken drive gear or stripped teeth inside the throttle body
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4
Corrosion or moisture ingress at the throttle body wiring connector
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5
Open or short circuit in the throttle motor drive wiring harness
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6
Faulty throttle position sensor (TPS) misreporting plate angle to PCM
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7
Vacuum leak downstream of a partially stuck plate masking position data
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8
PCM software fault or internal actuator driver failure (rare)
Symptoms drivers notice
How to diagnose P2112
A typical diagnostic flow when this code is present.
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1
Connect a scan tool, confirm P2112, record all co-stored codes, and capture freeze-frame data including throttle angle and commanded angle
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2
Inspect the throttle plate and bore for carbon deposits; attempt to move the plate by hand to check for mechanical binding
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3
Clean the throttle body thoroughly with throttle body cleaner; retest before further disassembly
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4
With a scan tool, observe live throttle position versus PCM command during key-on with engine off to verify motor response
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5
Test the throttle actuator motor for correct resistance and the motor drive wiring for opens, shorts, and voltage supply per the service manual
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6
Check all connector terminals and grounds in the throttle control circuit for corrosion, spread terminals, or moisture
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7
If mechanical and wiring checks pass, test the TPS for proper voltage sweep and replace if out of specification
Related powertrain codes
- B0001 — PCM Discrete Input Speed Signal Error
- B0004 — PCM Discrete Input Speed Signal Not Present
- C0359 — Four Wheel Drive Low Range (4LO) Discrete Output Circuit
- C0362 — 4LO Discrete Output Circuit High
- P2000 — NOx Adsorber Efficiency Below Threshold Bank 1
- P2001 — NOx Adsorber Efficiency Below Threshold Bank 2
Frequently asked questions
Can a stuck-closed throttle cause the car not to start?
Yes. If the throttle plate is fully closed and the PCM cannot command it open, the engine may be starved of air and fail to start.
Is P2112 different from P2111?
Yes. P2111 means the throttle is stuck open (an over-fuelling and runaway risk), while P2112 means it is stuck closed (an under-fuelling and stalling risk).
How often does throttle body cleaning actually fix P2112?
On high-mileage vehicles it resolves the fault a significant proportion of the time, especially when carbon buildup is visible.
What codes are commonly stored with P2112?
P2111 (stuck open — may alternate), P2101 (throttle actuator motor circuit range), P2135 (TPS A/B correlation), and various TPS low/high input codes are typical companions.
Do I need to recalibrate the throttle body after cleaning or replacement?
Most modern vehicles require a throttle body relearn or idle relearn procedure after cleaning or replacement.
Disabling P2112 in software
RaceTune can permanently disable P2112 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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