P1600 Honda/Acura Throttle Control Unit Failure
Code P1600 indicates an internal malfunction in the Throttle Control Unit (also known as the electronic throttle body or ETC module) on Honda/Acura vehicles. This code is set when the ECM/PCM detects a fault in the communication or internal operation of the throttle actuator control circuit. The electronic throttle control system (ETCS) replaces the traditional cable, and this code means the ECM cannot properly control the intake throttle plate position. It often relates to a faulty throttle body integrated circuit, pedal position sensor (APPS) voltage reference issues, or ECM control logic errors. It may appear alongside codes like P0606 (internal control module fault) or throttle position sensor codes.
01. Most Common Causes
- Internal failure of the electronic throttle body or throttle actuator
- ECM/PCM failure in the throttle control circuit
- Corrosion or damage to throttle body connectors
- Excessive resistance or open circuit in actuator control wiring
- Faulty or misadjusted accelerator pedal position sensor (APPS)
- ECM software update required
- Low system voltage or failure in the main PGM-FI relay module
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor throttle response or hesitation
- Engine stalling or rough idle
- Inability to accelerate smoothly
03. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect throttle body connector for corrosion, bent pins, or damage
Check throttle actuator control circuit wiring for opens, shorts, or high resistance
Test throttle position sensor and pedal position sensor signals with a multimeter or scope
Verify system voltage and PGM-FI relay operation
If all else passes, attempt ECM software update; if no update available, replace throttle body assembly
If problem persists, diagnose ECM internal fault or replace ECM
1. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive with code P1600. The vehicle may enter limp mode with reduced power, or the throttle may become unresponsive, increasing the risk of an accident. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
The cost to fix P1600 typically ranges from $200 to $800 USD. This includes diagnostic fees ($100-$150), throttle body replacement ($150-$400 for the part), and labor ($100-$250). ECM replacement or software updates may add additional cost.