P2118 Explained: Throttle Actuator Control Motor Current Range/Performance

Quick Answer

• What the code means: P2118 indicates that the engine control module (ECM) has detected a problem with the electric motor that controls the throttle body's throttle plate, specifically with the amount of electrical current it's using.
• Severity: High. This can cause the engine to stall or go into "limp mode," making it unsafe to drive. It is recommended to get this checked out as soon as possible.
• Most Common Cause: The most common cause for a P2118 code is a faulty throttle body assembly itself.

What the P2118 Code Means

The official OBD-II definition for P2118 is "Throttle Actuator Control Motor Current Range/Performance." In plain English, this means your car's computer has noticed that the electric motor responsible for opening and closing the throttle is drawing an unusual amount of electrical current.

Modern cars use a "drive-by-wire" system, where the gas pedal isn't mechanically connected to the engine. Instead, it sends an electronic signal to the ECM, which then commands a small motor—the throttle actuator control motor—to open or close a valve (the throttle plate). This regulates the amount of air entering the engine, controlling its speed and power.

The ECM constantly monitors the current draw of this motor. If the current is too high (indicating a struggle, like a jam) or too low (indicating a weak motor or bad connection), it triggers the P2118 code and usually puts the vehicle into a reduced power mode to prevent engine damage or unintended acceleration.

Common Symptoms

When the ECM logs a P2118 code, you will almost certainly notice drivability problems. Here are the most common symptoms:

• Check Engine Light is on
• Vehicle enters "limp mode" (drastically reduced engine power)
• Engine stalls, especially at idle
• Poor or no throttle response
• Rough running or unstable idle
• Difficulty starting the engine

Common Causes

While several issues can trigger a P2118, the causes are almost always located within the electronic throttle control system. Here they are, ranked from most to least likely:

1. Faulty Throttle Body Assembly: This is the most frequent culprit. The internal electric motor can fail, or the gears that move the throttle plate can become worn or bind. Carbon buildup can also restrict the plate's movement, causing the motor to work harder and draw more current.
2. Wiring or Connector Issues: A damaged wire, loose connection, or corrosion in the harness leading to the throttle body can cause erratic current readings.
3. Faulty Powertrain Control Module (PCM) or Engine Control Module (ECM): Though rare, the computer that controls and monitors the throttle body can fail. This should always be the last consideration after all other possibilities have been exhausted.

How a Technician Diagnoses It

A qualified technician will follow a systematic process to pinpoint the cause of a P2118 code.

1. Scan for Codes: The first step is always to connect a professional-grade OBD-II scanner to verify the P2118 code is present and check for any other related codes. The technician will document the freeze-frame data, which is a snapshot of the engine's operating conditions at the exact moment the code was set.
2. Visual Inspection: The technician will inspect the throttle body wiring harness and connectors for any obvious signs of damage, such as frayed wires, loose pins, or corrosion.
3. Scan Tool Data Analysis: Using the live data function on the scan tool, the technician will monitor the commanded throttle position versus the actual throttle position. A discrepancy between these two readings suggests a problem. They will also command the throttle open and closed with the scan tool to see if it moves smoothly.
4. Check for Carbon Buildup: The air intake boot will be removed to inspect the throttle bore and plate for heavy carbon deposits. If significant buildup is present, it can cause the throttle plate to stick.
5. Electrical Testing: If the wiring seems okay and the throttle plate is clean, the technician will use a digital multimeter (DMM) to test the motor circuit. They will check for proper voltage and ground at the throttle body connector. By comparing the motor's resistance to the manufacturer's specifications, they can determine if the motor itself has failed.

Typical Repair Cost

The cost to repair a P2118 code can vary significantly based on the vehicle and the specific cause.

• Throttle Body Cleaning: If the issue is simply heavy carbon buildup, cleaning the throttle body is a relatively inexpensive job. Expect to pay between $75 and $150.
• Throttle Body Replacement: This is the most common repair. A new throttle body assembly can cost anywhere from $200 to $600 for the part, depending on the make and model. Labor will add another $100 to $200. After replacement, a throttle body relearn procedure is often required, which the shop will perform.
• Wiring Repair: If a damaged wire is found, the cost will be primarily labor, typically falling in the $100 to $250 range.

Can I Keep Driving with This Code?

It is not recommended to keep driving with a P2118 code. The potential for the engine to stall or suddenly lose all power poses a significant safety risk, especially in traffic. When this code is active, the vehicle is unreliable and should be driven only as far as necessary to get to a repair shop.

Related Codes

Other codes related to the electronic throttle control system are often seen alongside P2118 or may indicate similar problems. These include:

• P2101: Throttle Actuator Control Motor Circuit Range/Performance
• P2110: Throttle Actuator Control System - Forced Limited RPM
• P2119: Throttle Actuator Control Throttle Body Range/Performance
• P0121: Throttle/Pedal Position Sensor "A" Circuit Range/Performance

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