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Service bulletin 3121

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 id10010248
Published by NHTSA2004-11-08
Manufacturer's number3121
Manufacturer's date2004-01-01
NHTSA componentENGINE AND ENGINE COOLING:COOLING SYSTEM

NHTSA's summary

EXHAUST VIBRATION RESONANCE OR MOAN IN VEHICLES WITH GEN III V8 ENGINES. *TC

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, Cooling system

Vehicles listed
CADILLAC ESCALADE2001, 2002, 2003, 2004, 2005
CHEVROLET AVALANCHE2001
CHEVROLET AVALANCHE2002, 2003, 2004, 2005
CHEVROLET SILVERADO2002, 2003, 2004, 2005
CHEVROLET TAHOE2000, 2001, 2002, 2003, 2004, 2005
GMC SIERRA1999, 2000, 2001, 2002, 2003, 2004, 2005
GMC YUKON XL2000, 2001, 2002, 2003, 2004, 2005
HUMMER H22003, 2004, 2005
HUMMER H2 SUT2004

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
34132005-10-28. Service bulletin. COOLANT LEAK. EARLY INDICATIONS POINT TO A CORROSION STRESS CRACK ON THE UPPER CLAMP AT THE LOWER RADIATOR HOSE TO THE WATER PUMP CONNECTION. ENGINEERNG IS TESTING....*TT
3431A2005-10-21. Service bulletin. SERVICE VME - COOLANT LEAK FROM RADIATOR SURGE TANK. *TT
0006020062005-03-10. Service bulletin. DEX-COOL ENGINE COOLANT INFORMATION. 2004 AND PRIOR PASSENGER CARS AND TRUCKS. *TT
3121A2004-11-03. Service bulletin. EXHAUST VIBRATION RESONANCE OR MOAN 99-05 FULL SIZE TRUCKS AND UTILITY VEHICLES WITH GEN 3 V-8 ENGINES. *TC
30722004-10-13. Service bulletin. THE ENGINE COOLANT TEMPERATURE OR INTAKE AIR TEMPERATURE SENSOR MAY READ -40 DEGREES WHEN MONITORED WITH TECH 2. *TT
020132004-05-26. Service bulletin. COOLANT LEAK FROM HEAD CUP PLUGS ON GEN III ENGINES. *MR
100120032004-05-06. Service bulletin. BLUEHEAT COOLANT HEATER THERMO TOP C. WEBASTO. *MR
030632004-02-24. Service bulletin. 03063 - OBD SYSTEM SOFTWARE UPGRADE - ON-BOARD DIAGNOSTIC (OBD) SYSTEM SOFTWARE UPGRADE - DIAGNOSTIC TROUBLE CODE (DTC) P0128 ENGINE COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE. *TT
0306020072003-12-02. Service bulletin. LOSS OF COOLANT. *TT
013392003-11-19. Service bulletin. HVAC BLOWER MOTOR FAN STAYS ON IN THE HIGH BLOWER POSITION. SERVICE VME. *TT