P1606 is a manufacturer-specific OBD-II diagnostic trouble code. Because it is manufacturer-specific, its exact definition depends entirely on the vehicle application, ranging from variable valve lift control faults to ABS communication issues.
The exact application must be verified before diagnosis. The code indicates the control module detected a fault, but testing is required to identify the root cause.
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Key Takeaways
- P1606 is a manufacturer-specific code, meaning its exact definition varies by automaker and vehicle application.
- On Nissan and Infiniti applications, it typically indicates a Variable Valve Event and Lift (VVEL) control module fault.
- On Volkswagen and Audi applications, it points to a Rough Road/Engine Torque Signal electrical malfunction from the ABS module.
- Diagnosis requires verifying the exact factory definition and testing the relevant control modules or communication circuits.
P1606 Code Description and Implications
P1606 is a manufacturer-specific powertrain code. Because the second digit is “1”, the definition is controlled by the automaker rather than the SAE standardized list.
Some Nissan and Infiniti applications: P1606 indicates a Variable Valve Event and Lift (VVEL) control module fault. The engine control module detects an issue with the VVEL system’s operation or communication.
Some Volkswagen and Audi applications: P1606 indicates a Rough Road/Engine Torque Signal electrical malfunction from the ABS control module. The ECM detects an invalid or missing signal used to prevent false misfire detection.
Some GM and Chevrolet applications: P1606 indicates a Serial Communication Problem with Device 6 or an electronic throttle control fault. When the control module detects an unexpected signal, it sets these trouble codes.
Common Causes of the P1606 Code
Possible causes depend entirely on the specific vehicle application.
For Nissan and Infiniti VVEL applications, a failing VVEL control module, damaged wiring or connectors, a faulty VVEL relay, or low battery voltage can trigger the code.
For Volkswagen and Audi applications, a faulty ABS control module, damaged wiring between the ABS and ECM, or poor electrical connections can cause the signal fault.
For GM applications, a serial communication wiring fault, a failing control module, or an electronic throttle control issue can trigger the code.
Symptoms Associated With P1606
The primary symptom is an illuminated Check Engine Light.
On Nissan and Infiniti applications, drivers may experience reduced engine performance, limp mode activation, rough idling, or engine stalling due to the VVEL system defaulting to a safe state.
On Volkswagen and Audi applications, symptoms may include ABS or traction control warning lights, and the engine may experience false misfire detection or erratic fuel trim adjustments on rough roads.
On GM applications, symptoms can include electronic throttle control issues, reduced power, or communication-related drivability concerns.
Diagnosing the P1606 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For Nissan and Infiniti applications, technicians inspect the VVEL control module wiring and connectors, test the VVEL relay, and verify battery and charging system voltage.
For Volkswagen and Audi applications, technicians inspect the wiring harness between the ABS module and the ECM, checking for opens, shorts, or corrosion in the rough road signal circuit.
For GM applications, technicians verify serial communication circuits and test the relevant control modules and throttle actuator components.
Repairing the P1606 Issue
Repairs follow the confirmed diagnosis for the specific application.
If the VVEL control module or its relay fails testing on a Nissan application, replacing the confirmed failed component resolves the fault. Repairing damaged wiring may also be necessary.
If the ABS module or the communication wiring fails testing on a Volkswagen or Audi application, repairing the harness or addressing the module fault restores the signal.
If a serial communication circuit is damaged on a GM application, repairing the wiring or replacing the faulty module resolves the issue.
Cost Considerations for P1606 Repairs
Repair costs vary depending on the underlying fault and the vehicle application.
Replacing a relay or repairing a damaged wire involves minimal parts and labor. Diagnosing and replacing a VVEL control module, ABS module, or addressing internal communication faults requires more diagnostic time.
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Prevention Strategies for Future Occurrences
Some electrical and mechanical failures cannot be reliably prevented.
Inspecting exposed wiring and keeping module connectors clean can help prevent moisture intrusion and corrosion that lead to communication and signal faults.
Maintaining the vehicle’s charging system and replacing aging batteries at the manufacturer-recommended intervals helps prevent low voltage conditions that can affect sensitive control modules.
Troubleshooting Tips and Best Practices
Never assume a manufacturer-specific code has a universal meaning. Always verify the exact factory service information for your specific vehicle.
Do not replace a VVEL or ABS control module without first verifying the wiring, connectors, and power supply circuits, as low system voltage or poor grounds often trigger these codes.
If P1606 is accompanied by other communication or low voltage codes, suspect a shared wiring harness issue, a failing battery, or a systemic ground fault rather than multiple simultaneous module failures.
More OBD-II Codes
| P1605 | P1604 | P1603 | P1602 |
| P1586 | P1587 | P1607 | P1608 |
| P1609 | P1610 | P1611 | P1612 |
| P0601 | P0602 | P0603 | P0604 |
| P0605 | P0606 | P0300 | P0607 |
| P0621 | P0622 | P0633 | P0638 |
Frequently Asked Questions
Is P1606 a generic OBD-II code?
No. P1606 is a manufacturer-specific code, meaning its exact definition and diagnostic procedure depend entirely on the vehicle’s make, model, and application.
Can I drive my vehicle with a P1606 code?
It depends on the application. If it triggers limp mode or affects the electronic throttle control, driving the vehicle can be unsafe and should be avoided until repaired.
Will a P1606 code cause my engine to stall?
Yes. On applications where P1606 indicates a VVEL control module or electronic throttle fault, the engine may default to a safe state, causing stalling or reduced power.
Does P1606 always mean the control module is broken?
No. The code often points to damaged wiring, a poor electrical connection, a failing relay, or low battery voltage rather than a mechanically or internally failed control module.
How do I clear a manufacturer-specific P1606 code?
Clearing the code requires fixing the underlying control module, wiring, or communication fault. Simply using a scan tool to erase the code will not repair the root cause.
What Should You Do About the P1606 Code?
Confirm the exact factory definition for your specific vehicle, then follow the applicable manufacturer diagnostic procedure for the relevant system and components.
Because P1606 is manufacturer-specific, testing the exact VVEL control modules, ABS communication circuits, or serial data lines identified by the factory service information is required to find the root cause.
Once the fault is confirmed, perform the necessary repairs and verify the fix by clearing the codes and completing a test drive.
