Understand & Fix P0223: Throttle Position Sensor B Circuit High Input with iCarsoft CR Ultra P

If your vehicle experiences sudden acceleration surges, unresponsive throttle, or fails to start, a diagnostic scan will likely return P0223. This OBD-II code stands for "Throttle Position Sensor (TPS) B Circuit High Input"—a critical fault targeting the secondary throttle position sensor (TPS B) and its control circuit. The TPS works with the Engine Control Module (ECM) to monitor throttle plate position, adjusting fuel injection and ignition timing for smooth performance. A "high input" error means the ECM detects a voltage signal above the normal range (typically 4.5V–5V), indicating the sensor or circuit isn’t providing accurate position data.

Basic scanners might only flag a "throttle system error" but can’t measure sensor voltage, test circuit continuity, or validate throttle actuator responsiveness—leaving you guessing between a faulty TPS, damaged wiring, or a failing throttle body. The iCarsoft CR Ultra P, with its OE-level engine diagnostics, bi-directional control, and live data tracking, solves this. Below, we break down P0223, its causes, symptoms, step-by-step resolution, and 8 FAQs to answer common troubleshooting questions.

What Is P0223?

P0223 focuses on the secondary throttle position sensor (TPS B)—a component integrated into the throttle body (alongside TPS A) in modern electronic throttle control (ETC) systems. TPS B acts as a backup to TPS A, verifying throttle plate position with redundant voltage signals. The sensor uses a potentiometer: as the throttle opens, voltage increases from ~0.5V (idle) to ~4.0V (wide open). When TPS B’s signal exceeds the ECM’s upper threshold (often 4.5V), the module triggers P0223. This high input usually stems from a shorted sensor, damaged wiring, or a malfunctioning throttle body—all of which disrupt throttle control and engine performance.

Key Symptoms of P0223

• Illuminated Check Engine Light: The primary warning sign, often paired with codes like P0123 (TPS A circuit high input) or P2111 (throttle actuator control system stuck open).
• Throttle Surges or Unresponsiveness: False high-voltage signals trick the ECM into thinking the throttle is open wider than it is, causing sudden acceleration or delayed response.
• Engine Stalling or No-Start: Severe TPS B faults can disable the ETC system, preventing the engine from cranking or staying running.
• Reduced Engine Power: The ECM may enter "limp mode" to protect the engine, limiting throttle opening to 20–30%.
• Rough Idle: Inaccurate throttle position data disrupts the air-fuel mixture, leading to shaky or unstable idle.
• Transmission Shifting Issues: Incorrect TPS signals can cause harsh or delayed gear shifts in automatic transmissions.

Common Causes of P0223

Why iCarsoft CR Ultra P Excels at Diagnosing P0223

The CR Ultra P outperforms basic tools with features tailored to throttle position sensor and ETC system diagnostics:

Step-by-Step: Diagnose P0223 with iCarsoft CR Ultra P

1. Confirm P0223 & Gather Data

   Plug the CR Ultra P into your vehicle’s OBD-II port, power on the tool, and select AutoVIN Identify to auto-detect your vehicle’s make, model, and ETC configuration.
   Navigate to Engine > Fault Codes > Read Codes to confirm P0223. Tap Code Details for model-specific insights (e.g., "Honda Civic: Throttle Position Sensor B Circuit High Input; Voltage: 4.9V, Expected: 0.5–4.0V; Check TPS B Wiring or Throttle Body").

2. Analyze Live TPS & ETC Data

   Go to Engine > Live Data > Throttle Control and monitor three key metrics:
   1. TPS B Voltage: Should fluctuate between 0.5V (idle) and 4.0V (wide open). A fixed reading above 4.5V confirms P0223.
   2. TPS A Voltage: Should mirror TPS B’s signal (within 0.1V). A large discrepancy indicates a faulty TPS B.
   3. Throttle Actuator Position: Use the CR Ultra P’s Throttle Actuator Test to verify if the throttle body moves as commanded.

3. Test the Throttle Position Sensor B (TPS B)

   1. Use Bi-Directional Control > Engine > Throttle Position Test: Send commands to open/close the throttle (0–100%) and check if TPS B’s voltage updates. No change = faulty sensor or throttle body.
   2. Locate the throttle body: Use the CR Ultra P’s Component Location tool (typically on the intake manifold).
   3. Inspect & Test: Check the TPS B connector for corrosion. Use the CR Ultra P’s Resistance Test to check the potentiometer (should match OEM specs, e.g., 5k ohms at idle—0 ohms = short; infinite = open).

4. Inspect Wiring, Fuses, & Throttle Body

   1. Wiring Check: Use Continuity Test to check TPS B wiring for breaks. Look for frayed wires near the throttle body or ECM connectors.
   2. Fuse/Relay Check: Navigate to Vehicle > Fuse Box Diagram (via the CR Ultra P) to find ETC-related fuses/relays. Test for continuity—replace any blown fuses.
   3. Throttle Body Check: Remove and inspect for carbon buildup. Clean the throttle plate with specialized cleaner if needed.

5. Repair & Clear the Code

   - Replace the throttle body (most TPS sensors are integrated) if tests confirm TPS B is faulty.
   - Repair damaged wiring, replace blown fuses/relays, or clean the throttle body as needed.
   - Reconnect the battery, use the CR Ultra P to Clear Codes, and run the Throttle Body Relearn function. Test drive to validate—ensure TPS B voltage fluctuates with throttle movement.

FAQs: P0223 Troubleshooting