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P1602

PCM Not Programmed.

  • Pontiac
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
6
AreaComputer and output circuits
02
FaultThe specific fault in that area

What it means

P1602 on a Pontiac means the powertrain control module (PCM) has detected that it has no valid programming or calibration loaded. This is usually set after a replacement or reprogramming job that was not completed, or when the stored software has become corrupted. The PCM cannot run its normal strategy without a valid calibration, so it logs the fault and may restrict engine operation.

Symptoms

  • Check engine light on
  • Engine cranks but will not start, or starts and stalls
  • Poor running, reduced power or limp-home behaviour
  • Transmission shifting harshly or stuck in one gear
  • Security or anti-theft light on or flashing
  • Scan tool shows no or incorrect calibration information

Possible causes

  • Replacement PCM fitted but not programmed with the correct software for the vehiclelikely
  • Reprogramming or software update interrupted or failed part-way throughlikely
  • Low battery voltage or unstable power supply during programmingpossible
  • Corrupted PCM memory or wrong calibration loaded for the model and enginepossible
  • Poor PCM power or ground connections causing a memory fault or resetpossible
  • Internal PCM fault preventing it holding its programmingrare

How to diagnose

  1. Read the stored codes and freeze frame data, and note whether P1602 is current or history only
  2. Find out whether the PCM has recently been replaced, repaired or reprogrammed, or the battery disconnected or flat
  3. Test battery condition and charging voltage, as low voltage can corrupt or interrupt programming
  4. Inspect PCM connectors, fuses, power feeds and earth connections for damage, corrosion or looseness
  5. Scan all modules for related codes, especially communication and security faults
  6. Check the calibration identification in the PCM against the correct one for the VIN, engine and transmission
  7. Confirm whether the model requires an anti-theft or security relearn after PCM programming; procedure varies by model and year

How to fix

  • Programme the PCM with the correct, current calibration for the vehicle, using a stable power supply
  • Repeat a failed or interrupted programming session after fixing the cause of the interruption
  • Carry out any required security or immobiliser relearn after programming, following the model-specific procedure
  • Repair faulty power, earth or connector problems affecting the PCM
  • Replace the PCM if it will not accept programming, then programme it correctly for the vehicle

Can I keep driving?

Medium severity

If the car starts and runs normally, it can be driven carefully for a short time to get it sorted, but do not leave it long. If it stalls, will not start or goes into limp mode, do not drive it and have it recovered for programming.

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

This code for other makes

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