P1602 Throttle Actuator Control Module Communication Fault
The P1602 code indicates a communication or PWM signal fault between the engine control module (ECM) and the electronic throttle body. The ECM detects that the command signal sent to the throttle actuator does not match the expected value, there is interference, or the throttle body control unit reports an internal processing error of the modulated signal.
01. Most Common Causes
- Faulty electronic throttle body (stepper motor, internal circuit board, or TPS sensor)
- Damaged wiring or connectors between ECM and throttle body (short to power/ground, open circuit, high resistance)
- Internal ECM failure (damaged PWM output driver)
- Low battery voltage affecting throttle adaptation
- Throttle adaptation/relearn required after battery disconnect or cleaning
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
03. Step-by-Step Diagnosis
Scan for additional codes and check freeze frame data
Inspect throttle body wiring and connectors for damage, corrosion, or loose pins
Test throttle body power and ground circuits with a multimeter
Check battery voltage and charging system (should be 12.6V+ engine off, 13.5-14.5V running)
Perform throttle body relearn procedure per manufacturer specifications
If wiring and voltage are OK, test throttle body actuator and position sensors; replace if faulty
If throttle body tests good, suspect ECM failure and test/replace ECM
1. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The vehicle may enter limp mode with reduced power, increasing the risk of accidents. Have it diagnosed and repaired immediately.
How much does it cost to fix?▼
Repair costs vary widely: throttle body replacement $200-$600, wiring repair $100-$300, ECM replacement $500-$1500. Diagnosis typically $100-$150.