Throttle Control Unit Modulated Command Malfunction
Your engine's throttle control computer is receiving conflicting or invalid commands, like a driver trying to press the gas pedal but the signal is getting scrambled. This prevents the engine from responding properly to acceleration requests.
The ECM monitors the electronic throttle actuator commands and verifies that actual throttle position matches requested position within a specific time window. If the modulated signal deviates beyond acceptable parameters or the throttle fails to respond to commands, a fault is detected.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Command-to-Actual Position Delta | Within 2-5% correlation | Deviation exceeds 10% for >2 seconds |
| Signal Integrity Check | Clean, stable voltage signal | Intermittent dropouts or noise detected |
Code P1602 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1602 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.