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Home/DTC Codes/Pontiac/Sunfire/1995-2005 2.2L I4/U0100
U0100

Lost Communication with ECM/PCM

1995-2005 Pontiac Sunfire 2.2L I4

Critical SeverityNetworkGeneric (SAE)

Description

The diagnostic system cannot communicate with the Engine Control Module.

Symptoms

  • Multiple warning lights
  • Engine may not start
  • Many systems inoperative
  • Cannot read engine codes

Common Causes

  • PCM power or ground failure
  • CAN bus wiring issue
  • PCM failure
  • Fuse blown
  • Wiring harness damage

Diagnostic Steps

  1. Check PCM fuses
  2. Test PCM power and ground circuits
  3. Check CAN bus wiring to PCM
  4. Try communicating with other modules
  5. Inspect wiring harness

Repair Notes

Check fuses and power supply to PCM first. CAN bus issue is second most common.

Related Codes

P0600Serial Communication LinkU0001High Speed CAN Communication BusU0101Lost Communication with TCM

Other Network Codes

U0100 on Other Vehicles

Pontiac Aztek

2001-2005 3.4L V6

Pontiac Bonneville

1990-1999 3.8L V6

Pontiac Bonneville

2000-2005 3.8L V6

Pontiac Bonneville GXP

2000-2005 4.6L V8

Pontiac Bonneville GXP

2000-2005 4.6L V8 Northstar

Pontiac Bonneville SSEi

1992-1999 3.8L Supercharged V6

Pontiac Bonneville SSEi

1992-1999 3.8L V6 Supercharged

Pontiac Firebird

1993-1997 3.4L V6

Common Questions

What does code U0100 mean on a 1995-2005 Pontiac Sunfire?

U0100 stands for "Lost Communication with ECM/PCM". The diagnostic system cannot communicate with the Engine Control Module.

What are the symptoms of U0100 on a Pontiac Sunfire?

Common symptoms of U0100 include: Multiple warning lights, Engine may not start, Many systems inoperative, Cannot read engine codes.

What causes U0100 on a 1995-2005 Pontiac Sunfire?

Common causes of U0100 include: PCM power or ground failure, CAN bus wiring issue, PCM failure, Fuse blown, Wiring harness damage.

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