U0140 on Pontiac: How to Diagnose & Fix
Lost Communication with BCM
1 Pontiac model · 1 documented issue
U0140 on Pontiac by model: symptoms, diagnosis and fix
Common G6 fault pattern: simultaneous Service StabiliTrak, Service Traction Control, ABS warning lights, and sometimes Reduced Engine Power message. GM-acknowledged issue (TSB 08-05-22-009, later safety recall 14V252000 covering 2005-2010 G6) traced to fretting corrosion and increased resistance on terminals of the Body Control Module connectors (the C2/X2 connector), reached behind the right-side front floor console side trim panel in the passenger footwell; the resulting brake apply sensor signal fault can disable traction control and StabiliTrak. Micro-vibration causes oxidation on the contact surfaces; moisture intrusion from sunroof drains can accelerate it.
Common Symptoms
- Service StabiliTrak and Service Traction Control messages
- ABS warning light
- Reduced Engine Power message
- Intermittent communication codes (U-codes)
How to Fix
First check the VIN for open safety recall 14V252000 (GM 13036): the dealer attaches the BCM harness with a spacer, applies dielectric lubricant to the BCM X2 and brake apply sensor connectors and relearns the brake pedal home position free of charge. Remove the right-side front floor console side trim panel to access the three large BCM connectors (especially the C2 connector); unlatch via the plastic levers, inspect for green/fretting corrosion, clean with electrical contact cleaner, apply dielectric grease per GM procedure (one-inch nylon bristle brush on C2 pins), and re-seat several times. Note: the 'Reduced Engine Power' message specifically is often caused by a separate IP-to-body harness connector in the DRIVER-side (left) kick panel carrying the APP signal — inspect both sides. Do NOT replace the BCM for this condition. Also scan wheel-speed and steering-position sensors before condemning the BCM.
Sources for this issue (5)
- GM Recall Bulletin 13036B (NHTSA 14V-252): Brake Lamp Malfunction, 2005-2010 Pontiac G6recall
- GM Recall Bulletin 08317 (NHTSA 09V-036): Brake Lamps Not Working Properly, 2005-2006 Pontiac G6 (connector fretting corrosion)recall
- SOLVED: Traction control light (and abs light) - iFixitforum
- Reduced Engine Power and Service Traction Control - Pontiac G6 Forumforum
- ABS and Traction Control Light - Pontiac G6 Forumforum
U0140 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0140 mean on a Pontiac?
U0140 stands for "Lost Communication with BCM." U0140 is a network communication code meaning a module has lost communication with the body control module (BCM) over the vehicle's data bus. The BCM oversees many body and convenience functions — lighting, door locks, windows, wipers, anti-theft, and gateway communications — so losing contact with it can cause a wide range of seemingly unrelated electrical problems and warning lights. This is typically a wiring, connector, power/ground, or bus fault, or a failure of the BCM itself. Because the BCM often acts as a communication hub, this code can appear alongside other 'lost communication' codes. On Pontiac it is documented across 1 model: G6.
What are the most common causes of U0140?
The most common causes of U0140 are: Loss of power or ground to the BCM, CAN/data bus wiring damage, short, or open circuit, Corroded, loose, or damaged BCM connectors, Blown fuse feeding the BCM, Failed body control module, Water intrusion or corrosion in the harness, Another module faulting the shared data bus. The specific cause varies by vehicle.
How much does it cost to fix U0140 on a Pontiac?
Repair costs vary widely with the root cause and Pontiac model; each issue on this page carries its own estimate where one is published.
Looking for U0140 on a different make?
View U0140 across all makes →Join 700+ subscribers following Au7o for vehicle insights and updates.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.