hardly worth mentioning
Crashes / Fires:
0 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
94,818 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2003 Chevrolet Trailblazer EXT cooling system problems

cooling system problem

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2003 Chevrolet Trailblazer EXT Owner Comments

problem #5

Jul 192010

Trailblazer EXT

  • 100,000 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.

- Concord, CA, USA

problem #4

Oct 012009

Trailblazer EXT

  • 89,000 miles
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.

- Steamboat Springs, CO, USA

problem #3

Jul 262009

Trailblazer EXT

  • 156,000 miles
2003 trailblazer transmission lines. Coolant lines rusted at the factory connection. Major fluid loss, had to repair immediately.

- Clinton, 00, USA

problem #2

May 012007

Trailblazer EXT

  • 47,000 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.

- Cooper City, FL, USA

problem #1

Apr 202007

Trailblazer EXT 4WD 6-cyl

  • Automatic transmission
  • 82,090 miles
I own a 2003 Chevy trailblazer lt @ 35,825 miles I reported my vehicle binds up on turns & of course the garage found nothing (drove it 20 miles for comparison @ the time). So now that I am up to 82,090 miles now I mention suspension issues still & of course they find both lower ball joints need replaced @ $320.06 & left outer tie rod end broken @ $170.80. Also they inform me I need to replace 3 of my 4 stabilizer bar links are loose & rattling @ an estimate of $320 (haven't done yet) also, I have looked on a website called mycarstats.com & found many others with these same issues with this vehicle @ much lower mileage & where tie rod issue caused an accident -- they weren't as lucky as me. Also people I work with who have this same yr & model vehicle have had to have ball joints, sway bars replaced, and other suspension work @ lower mileages. I also had an issue with my 4-wheel drive becoming inoperative & this did almost cause me to wreck going up hill during winter weather. They replaced front differential engagement actuator. All these things in my mind should not have happened at these mileages. The 4-wheel drive quit @ 80,000 miles. All these issues can create safe driving issues for the consumer especially someone who pays over $30,000 for a vehicle when it's new. Let me add now that the latest expensive repair to add to my list is the fan clutch assembly on my engine cooling fan system $573 -- also found many GM owners of Bravada, rainers, Envoy & trailblazers experiencing this items failure too.

- Port Allegany, PA, USA

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