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P1608

Serial Communication Problem With Device 8.

  • Buick
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
6
AreaComputer and output circuits
08
FaultThe specific fault in that area

What it means

On a Buick, P1608 means the engine control module has lost or received invalid serial data communication with another control module on the network, referred to as 'Device 8'. The module expects regular messages from that device and logged a fault when they stopped or were corrupt. Which module counts as Device 8 depends on the model, year and engine, so check the manufacturer's data for your vehicle.

Symptoms

  • Check engine light on
  • Other warning lights on the dash, such as ABS, traction control or airbag
  • Erratic or inoperative gauges or instrument cluster functions
  • Poor shifting or the gearbox stuck in a fixed gear on some models
  • Hesitation, rough running or reduced performance in some cases
  • Intermittent no-start or hard starting

Possible causes

  • Damaged, corroded or loose wiring or connectors in the serial data circuit to Device 8likely
  • Low battery voltage, poor battery terminals or weak earth connections upsetting module communicationlikely
  • Device 8 module not powering up due to a blown fuse or a lost power or earth supplypossible
  • Faulty Device 8 control modulepossible
  • Aftermarket electrical accessories or poor previous repairs interfering with the data networkpossible
  • Internal fault in the engine control module or outdated softwarerare

How to diagnose

  1. Read all stored and pending codes from every module and note any other communication or power-supply codes
  2. Review freeze frame data and find out when the fault set, such as at start-up, on bumps or in wet weather
  3. Check battery condition and charging voltage, and inspect the terminals and main earth points
  4. Look up which module is Device 8 for this model and year in the manufacturer's information
  5. Check the fuses and power and earth supplies to that module
  6. Inspect the serial data wiring and connectors for chafing, water ingress, corrosion or pushed-back pins
  7. Test the data circuit for continuity, short circuits and signal activity using the wiring diagram
  8. Check for outstanding software updates and bulletins for the vehicle

How to fix

  • Repair or replace damaged wiring and clean or replace corroded connectors
  • Restore a healthy battery and charging system and fix poor earth connections
  • Replace blown fuses after finding out why they failed, and restore the power supply to the module
  • Replace or repair the faulty Device 8 module, with programming where required
  • Remove or correct faulty aftermarket electrical fittings
  • Update the control module software if an outdated calibration is a known cause for this model

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but get it checked soon as the affected system may behave unpredictably or stop working. Stop driving if the car stalls, shifts badly or shows safety-related warnings such as ABS or airbag lights.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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