What Does P1606 Mean?
This code indicates an electrical malfunction in the communication circuit between the ABS ECU and the engine ECU for the rough road detection / engine torque specification signal. The ABS module sends wheel speed variation data to the PCM so it can distinguish engine misfires from road-surface-induced crankshaft speed variations. Without this signal, the PCM may set false misfire codes on rough roads.
Common Causes
25%
Faulty ABS control module with degraded communication output
25%
Damaged wiring between ABS ECU and engine ECU for the torque signal
20%
Corroded connector at the ABS module or PCM for this specific signal line
15%
ABS module not powered or in fault mode, unable to send torque signal
15%
PCM rough road detection input circuit failure
Diagnostic Steps
1
Check for any ABS-related DTCs stored in the ABS module; a primary ABS fault may be preventing the torque signal from being transmitted.
2
Verify the ABS module is powered and communicating by confirming ABS PIDs are available on the scan tool.
3
Locate the dedicated signal wire between the ABS ECU and PCM (this is often separate from the main CAN bus); check for continuity and proper voltage levels.
4
Inspect connectors at both the ABS module and PCM for the rough road signal pin—check for corrosion, bent pins, or backed-out terminals.
5
If the wiring is intact and the ABS module is functioning, the PCM input circuit may be faulty; verify by checking signal presence at the PCM connector with an oscilloscope.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
This code indicates an electrical malfunction in the communication circuit between the ABS ECU and the engine ECU for the rough road detection / engine torque specification signal. The ABS module sends wheel speed variation data to the PCM so it can distinguish engine misfires from road-surface-indu...
The most common cause of P1606 (Rough Road Spec. Engine Torque ABS-ECU Electrical Malfunction) is: Faulty ABS control module with degraded communication output
Typical repair costs for P1606 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
No direct safety impact. The primary consequence is false misfire detection codes on rough road surfaces, which may illuminate the check engine light and potentially cause unnecessary catalyst protection measures like fuel cutoff to individual cylinders.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1606 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / ABS Communication
Difficulty
Type
Manufacturer
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