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P1602

PCM Not Programmed.

  • Plymouth
  • Powertrain
  • Manufacturer code
  • High 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 Plymouth means the powertrain control module (PCM) has detected that it has not been programmed, so it does not hold valid calibration or configuration data. This typically follows a PCM replacement, a failed or interrupted reflash, or corrupted memory. The PCM sets the code because its stored programming is missing or fails validation.

Symptoms

  • Engine cranks but will not start
  • Malfunction indicator lamp on
  • Engine runs poorly, stalls or goes into a limited operating mode
  • Poor or erratic gear changes on automatic models
  • Security or immobiliser warning light on or flashing
  • Scan tool cannot communicate properly with the PCM or shows missing calibration

Possible causes

  • Replacement PCM fitted but not yet programmed or configured for the vehiclelikely
  • Interrupted or failed software update or reflash, for example from a voltage drop during programminglikely
  • Corrupted PCM memory or internal PCM faultpossible
  • Low or unstable battery voltage or poor PCM power and earth connections causing a programming or memory errorpossible
  • Incorrect or outdated calibration loaded for the vehicle's engine and transmissionpossible
  • Damaged wiring or connectors to the PCM, or water ingress into the PCMrare

How to diagnose

  1. Record the freeze frame data and all stored codes, and note whether any other module codes are present
  2. Ask about recent work: PCM replacement, reflash, battery disconnection or flat battery
  3. Check battery condition and charging voltage, and clean and tighten battery terminals
  4. Inspect PCM power feeds, earths and connectors for corrosion, damage, water ingress or loose pins
  5. Check that the PCM part number matches the vehicle's engine, transmission and market for the model year
  6. Confirm whether the PCM communicates and whether the code is current or has just been stored
  7. Check the manufacturer's service information for the correct programming procedure for the model and engine, and the latest valid calibration

How to fix

  • Programme the PCM with the correct, current calibration and complete any required vehicle configuration and security or key learn procedures, using a stable power supply during programming
  • Repeat a failed reflash after correcting the cause, such as low battery voltage
  • Charge or replace a weak battery and repair poor power or earth connections
  • Repair damaged wiring or connectors, and dry out and address any water ingress
  • Replace the PCM if it will not accept programming, then programme it to the vehicle

Can I keep driving?

High severity

The car may not start, and if it does it may run in a limited mode or stall unpredictably, so do not rely on it for driving. Have it programmed or repaired before further use.

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

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