2003 Chevrolet Trailblazer EXT Engine cooling Problems
- Complaints
- 16about this part
- Share
- 5%of 313 total for the year
- Median mileage
- 69,060miles
- Trend
- StableComplaints filed in the last 3 full calendar years are within 25% of the 3 years before.
NHTSA recorded 16 complaints about the engine cooling of the 2003 Chevrolet Trailblazer EXT, 5% of the 313 complaints for this model year. Where a mileage was given, the median is 69,060 miles.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“Antifreeze is leaking from rear heater core. Caused my engine to overheat. Fluid leaks at a fairly rapid rate. In doing research I found that they changed the heater core so this repair costs an extra $500 for parts to retrofit a new heater core. If there is a flaw in the design why isn't this a recall? It could cause engine damage. I called GM with no luck.”
NHTSA complaint #10294970, filed 2009-12, 89,000 miles“Trailblazer over heated about a year ago, ran diagnostics-changed the fan clutch assy, worked for two months. Over heated again- more diagnostics-warranty fan clutch, worked for a week- warranty fan clutch again and changed the coolant temp sensor- still over heating. Dealership wanted to change the fan clutch again- I refused because this is about to run me into the poor house.”
NHTSA complaint #10234416, filed 2008-07, 47,000 miles“Thermostat has failed twice during long trips. This causes the engine to run hot or cold. I am on my third one and have concluded it must be a design defect. Failure of this component may cause the engine to fail and thus strand the driver.”
NHTSA complaint #10343895, filed 2010-07, 100,000 miles“2003 chevy trailblazer transmission. . I usually have to stop, put the car in park, and then back in drive once or twice to get first gear to engage. Also, when passing or accelerating on the freeway, I am losing power.”
NHTSA complaint #10268591, filed 2009-05, 165,000 miles“Where should I start? Purchased 03 trailblazer in 2/08 w/only 60,000 miles. Has been in shop 3 months..lost count of costs. A/c and heat not working properly..no hot air; clutch fan replaced; transmission slipping; engine cuts off while at stop-light. Should I go on? You would think w/only 60,000 miles on it--it was just getting broken in. I have never been so disappointed in a truck before..now I am stuck with the truck and its payment...no more money to repair and can't afford to trade in.”
NHTSA complaint #10243198, filed 2008-09, 60,000 milesRelated service bulletins
- 10251887Mar 14, 2024This bulletin advises the technician of possible location of an internal coolant leak from a specific cylinder head and location.
- 10251890Mar 13, 2024This 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…
- 10250775Feb 22, 2024This 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…
- 10249579Jan 12, 2024This PI bulletin advises the technician on the proper way to install the pistons in an engine.
- 10242843Sep 1, 2023The service bulletin advises the tech of a normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the…
- 10242262Aug 24, 2023This service bulletin provides graphics, information and guidelines for engine component wear to assist service personnel as a guideline to perform necessary engine repairs and…
- 10235802Apr 24, 2023This diagnostic tip bulletin provides additional information on how to diagnose a possible valve, lifter or camshaft issue.
- 10234141Mar 23, 2023This diagnostic tip bulletin provides additional information on how to diagnose a possible valve, lifter or camshaft issue.
- 10234110Mar 17, 2023This service bulletin provides service information on new torque specification and installation procedure for ACDelco Spin-On Oil Filters.
- 10228888Dec 14, 2022This service bulletin provides diagnostic tips/steps on testing for possible EVAP leaks in the system to correct a customer concern of an MIL Illuminated with DTCs P0442 and/or…
Engine cooling: other model years
Other parts of the 2003 Chevrolet Trailblazer EXT
89 complaintsElectrical system
77 complaintsTransmission and drivetrain
49 complaintsVisibility (wipers, defrost, mirrors)
26 complaintsExterior lighting
23 complaintsBody and structure
20 complaintsBrakes
13 complaintsLatches, locks and linkages
13 complaintsSuspension
12 complaintsOther or unknown
7 complaintsVehicle speed control
7 complaintsSteering
6 complaints
← All problems reported for the 2003 Chevrolet Trailblazer EXT
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 27, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology