Engine-Codes - Generic - U1102

U1102 - Invalid Or Missing Data For Primary Id

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

U1102 Possible Causes

  • Faulty / intermittent ignition switch connections
  • J1850 / SCP / CAN Bus wiring intermittently open, shorted to power or ground
  • Faulty / intermittent connection at the Powertrain Control Module (PCM)
  • Faulty / intermittent connection at the Body Control Module (BCM)
  • Faulty / intermittent connection at the Instrument Panel Cluster (IPC)

How is the U1102 code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes

This is typically an electrical wiring connection issue at one of the controllers being monitored by the manufacturer.
It can occur if:
Someone changes a battery while the ignition switch is left on, that is, left in the RUN position.
Someone flashes/upgrades their engine controller – other modules unable to communicate with PCM during this process – this will set U1102 at a multitude of controllers on the vehicle – all false codes. Erase and carry on.
May need to disconnect both battery cables and touch them together for 15 seconds. Reattach battery cables, positive first, then negative and see if a soft reset helps.

What is the cost to diagnose the U1102 code

Labor: 1.0

The cost to diagnose the U1102 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
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When is the code detected?

When the Powertrain Control Module (PCM) is unable to communicate with any other controller on the bus network at any time while the ignition switch is in the RUN position.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine won’t crank / cranks but fails to start
  • Instrument panel gauges inoperative
  • Power windows / door locks intermittently operate
  • May or may not be able to communicate with a scan tool / depends on problem

U1102 Meaning

This is a manufacturer specific fault code and can be used for several different faults, depending upon what the manufacturer wants to use it for. Controllers communicate over the Serial Communication Protocol (SCP) bus network, also known as J1850 bus, or Controller Area Network or CAN Bus. These bus communication systems may or may not be fault tolerant, which means any type of intermittent/loose connection between these controllers could cause communication to stop. When these controllers are unable to communicate with each other at any time while the ignition switch is turned on, code U1102 will set.

More Information

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Information for specific makes

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