P2107

Actuator Control Module Processor

P2107 is a generic OBD-II powertrain diagnostic trouble code: Actuator Control Module Processor. 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.

Code
P2107
Group
Powertrain
System
SCR/AdBlue
Severity
Critical (limp mode / no-start)
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What P2107 means

P2107 is set when the throttle actuator control (TAC) module fails its own internal processor self-test. On most modern vehicles the TAC function is integrated into the PCM, but on some platforms (notably Ford, Lincoln, and Mazda) a discrete TAC module handles throttle control independently. Either way, the module continuously runs internal diagnostics on its processor, memory, and communication paths. If a RAM check, ROM checksum, clock integrity test, or similar internal routine returns a failure, the module sets P2107 and immediately initiates fail-safe throttle operation.

The fail-safe response to P2107 is typically more severe than for most other TAC codes: the engine may be held at idle or may fail to start entirely, and a 'Reduced Engine Power' message or amber wrench lamp typically appears alongside the MIL. Because the fault is internal to the module's processor — rather than in an external sensor or wiring — conventional circuit testing will often find nothing wrong. The fix frequently requires TAC module or PCM replacement, or in some cases a software/calibration update that resolves a processor initialisation bug.

Before condemning the module, confirm there are no power supply or ground integrity issues at the TAC module connector, as low supply voltage or a poor ground can corrupt processor operation and generate false P2107 codes that resolve after the supply circuit is restored. A scan tool that can command TAC module self-test routines will help confirm whether the fault is repeatable.

Common causes

Most-frequently reported root causes when P2107 is logged.

  • 1
    Internal TAC module or PCM processor fault (RAM, ROM, or clock integrity self-test failure).
  • 2
    Low or noisy supply voltage at the TAC module — inadequate power corrupts processor operation.
  • 3
    Poor or high-resistance ground connection at the TAC module causing reference voltage instability.
  • 4
    Failed accelerator pedal position (APP) sensor assembly generating implausible input signals that trigger a processor fault flag.
  • 5
    Damaged wiring or connector between the PCM and a discrete TAC module (where fitted) disrupting inter-module communication.
  • 6
    Throttle body assembly fault causing the TAC processor's closed-loop monitoring to detect an unresolvable internal conflict.
  • 7
    Software corruption or calibration error in the TAC module (resolved via reprogramming rather than hardware replacement).

Symptoms drivers notice

MIL illuminated along with a 'Reduced Engine Power' warning or amber wrench/spanner lamp.
Engine enters limp mode immediately — throttle response is severely restricted or absent.
Engine may stall at idle or fail to start if the TAC module fault is severe.
Cruise control and traction/stability control systems disabled as a secondary effect of TAC failure.
Fault may be intermittent, clearing on a cold start but returning after the module warms up.

How to diagnose P2107

A typical diagnostic flow when this code is present.

  1. 1
    Scan for all stored and pending codes; address any APP sensor codes (P0120, P0220, P0225), TAC motor codes (P2100–P2104), or communication codes (U-codes) before P2107, as these can trigger the processor fault secondarily.
  2. 2
    Check TAC module (or PCM) supply voltage and ground integrity: measure battery voltage at the module connector with the ignition on and verify ground pin resistance to chassis ground is below 0.3 Ω.
  3. 3
    Inspect the accelerator pedal position sensor connector and harness; APP sensor signal implausibility can trigger TAC processor fault flags.
  4. 4
    Clean the throttle body plate and bore; a mechanically binding throttle can produce feedback that the processor interprets as a control loop failure.
  5. 5
    Check for available TAC module or PCM software/calibration updates via manufacturer TSBs — P2107 on some Ford/Lincoln/Mazda platforms is caused by a processor initialisation bug resolved by reprogramming.
  6. 6
    If supply voltage, grounds, external sensors, and software updates have all been verified, replace the TAC module (discrete) or throttle body assembly with integrated module as applicable.
  7. 7
    After replacement, perform the required throttle body relearn or TAC module initialisation procedure, then clear codes and complete a full drive cycle to confirm resolution.

Related powertrain codes

Frequently asked questions

Why does P2107 point to an internal processor error rather than a wiring fault?

Unlike codes for external sensors or circuits, P2107 is generated by the TAC module's built-in self-diagnostics — the same way a computer reports a hardware fault. The module checks its own RAM, ROM, and timing circuits on every key cycle; a failure there sets P2107 regardless of external wiring condition.

Can low battery voltage cause P2107?

Yes. If the supply voltage drops below the TAC module's minimum operating threshold during cranking or from a weak battery, the processor may fail to initialise correctly and set P2107. Always verify charging system and battery health before replacing the TAC module or PCM.

Is reprogramming a genuine fix for P2107 or just a temporary workaround?

On affected Ford, Lincoln, and Mazda platforms, a software update corrects a bug in the TAC processor initialisation sequence. This is a permanent fix, not a workaround. If the code returns after reprogramming, it indicates a genuine hardware fault requiring module or throttle body replacement.

Can P2107 appear alongside P2100 or P2101 on the same scan?

Yes. When the TAC processor detects an irrecoverable internal error, it may simultaneously log motor circuit codes because the entire throttle control strategy is disrupted. In that scenario, P2107 is the root cause code; address it first, and the accompanying TAC codes will typically clear once the module fault is resolved.

Disabling P2107 in software

RaceTune can permanently disable P2107 — 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.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

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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