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Service bulletin 3950

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10020968
Published by NHTSA2007-02-02
Manufacturer's number3950
Replaces3950C
NHTSA componentENGINE AND ENGINE COOLING:ENGINE

NHTSA's summary

INTERMITTENT SERVICE 4 WHEEL DRIVE LAMP ON AND CODE C0378. *KB UPDATED 10/03/07. *NJ

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Engine

Trouble codes named

C0378

Vehicles listed
CHEVROLET AVALANCHE 15002007 (the catalog's model; the bulletin names a series or trim of it)
CHEVROLET AVALANCHE 25002007 (the catalog's model; the bulletin names a series or trim of it)
CHEVROLET SUBURBAN 15002007 (the catalog's model; the bulletin names a series or trim of it)
CHEVROLET TAHOE2007
GMC YUKON2007

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
03-06-01-023I2025-01-17. Service bulletin. This service bulletin explains how to measure for oil consumption and possible reasons for loss of oil.
03-06-01-023H2024-11-14. Service bulletin. This service bulletin explains how to measure for oil consumption and possible reasons for loss of oil.
04-06-04-051J2024-10-31. Service bulletin. This service bulletin provides information for maintenance cleaning of the fuel injectors and gasoline detergent additive.
09-06-04-026Y2024-09-05. Service bulletin. This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2.
01-06-01-011P2024-09-05. Service bulletin. This service bulletin provides guidelines and diagnostic/repair information to technicians regarding vehicle engine oil consumption.
16-NA-3832024-07-16. Service bulletin. This service bulletin advises of a new fuel injection cleaner kit used for decarbonizing the intake valves to correct conditions of rough idle, Crank no start, extended crank or misfire, MIL with DTCs, and explains how Top Tier fuels should be used to reduce carbon build-up.
15-00-89-004G2024-05-15. Service bulletin. This service bulletin provides technicians with information to help identify the differences between what is considered a fluid leak, and what is considered fluid seepage.
16-NA-3832024-03-19. Service bulletin. This technical bulletin advises of a new fuel injection cleaner kit used for decarbonizing the intake valves to correct conditions of rough idle, Crank no start, extended crank or misfire, MIL with DTCs, and explains how Top Tier fuels should be used to reduce carbon build-up.
22-NA-0742024-02-29. Service bulletin. This service bulletin provides service information to technicians on guidelines to replace Oil Cooler, Oil Cooler Lines and Oil Tank if the engine was replaced where large amounts of debris has flowed throughout the oiling system.
16-NA-3382024-02-17. Service bulletin. This Warranty Admin service bulletin provides guidelines for Dealers Not Required and for Dealers Required to Contact the PQC for engine or transmission assembly replacement and explains the PQC process, GWM Transaction submission, vehicle service record retention and proper handling of assembly returns for Canadian Dealers only.