The 2021 Colorado ZR2 is a capable off-road midsize truck available with a 3.6L V6 or 2.8L Duramax diesel. The diesel variant has serious reliability concerns centered on catastrophic engine failures, while the V6 is generally solid but faces transmission cooling and mount issues.
Symptoms: sudden loss of power under load, severe knocking or rattling from engine block, metal shavings in oil, white or blue smoke from exhaust, check engine light with misfire codes
Fix: Complete engine rebuild or replacement required — crankshaft, pistons, rings, bearings all commonly damaged together. This is a known weakness in the LWN Duramax when oil supply is compromised or crankshaft bearings fail prematurely. Expect 20-30 labor hours for rebuild, 12-16 hours for used engine swap. Many owners opt for GM reman long block.
Estimated cost: $8,000-15,000
Transmission Oil Cooler Line Leaks
Common · medium severity
Typical onset: 40,000-80,000 mi
Symptoms: transmission fluid puddles under vehicle, low transmission fluid warning, harsh shifting when fluid level drops, fluid visible along cooler lines at radiator
Fix: The cooler lines rust and corrode at fittings, particularly where they connect to the radiator. Replace both lines as a set — trying to reuse old fittings leads to repeat failures. 2-3 labor hours, includes fluid refill and system flush.
Estimated cost: $400-700
Transmission Mount Failure
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: clunk when shifting from park to drive or reverse, excessive vibration at idle in gear, visible tearing or separation of rubber mount, transmission appears to sag when inspected on lift
Fix: The rubber isolator in the transmission mount degrades, especially on trucks that see off-road use or towing. The ZR2's suspension articulation accelerates wear. Replace mount assembly — 1.5-2 labor hours. Inspect transfer case mount at same time as it often fails concurrently.
Estimated cost: $250-450
Diesel Fuel Filter Clogging (2.8L Only)
Common · medium severity
Symptoms: hard starting especially in cold weather, loss of power under acceleration, engine stalling at idle, check engine light with fuel pressure codes P0087/P1093
Fix: The diesel fuel filter on the LWN requires replacement every 15,000-20,000 miles despite GM's longer recommended interval, particularly with poor fuel quality. Water contamination accelerates clogging. Filter and housing replacement takes 0.5-1 labor hour, but many DIY-ers struggle with primer procedure.
Estimated cost: $150-300
Diesel Head Gasket Failure (2.8L Only)
Occasional · high severity
Typical onset: 80,000-140,000 mi
Symptoms: white smoke from exhaust on cold start, coolant loss with no visible leaks, rough idle and misfires, milky oil on dipstick or oil cap, overheating under load
Fix: The LWN Duramax head gaskets fail more frequently than expected, often related to cooling system contamination or EGR cooler issues that cause hotspots. Both heads typically need gaskets, ARP studs recommended over OEM bolts for longevity. 14-18 labor hours, requires head resurfacing.
Estimated cost: $3,500-5,500
8-Speed Automatic Harsh Shifts (V6 Models)
Occasional · low severity
Typical onset: 30,000-70,000 mi
Symptoms: hard 1-2 or 2-3 shifts especially when cold, delayed engagement from stop, occasional flare between gears, transmission learns wonky shift patterns
Fix: The 8L45 transmission in V6 models develops harsh shift quality, often correctable with fluid exchange using full-synthetic ATF and TCM reprogramming. If mechanical damage has occurred (rare), valve body replacement needed — 6-8 labor hours. Start with fluid service first (1.5 hours).
Estimated cost: $200-400 fluid service, $1,200-2,000 valve body
Owner tips
If buying diesel: demand oil analysis history and inspect for metal in oil filter — walk away from any engine with bearing material present
Change transmission fluid every 40,000-50,000 miles regardless of GM's 'lifetime fill' claim — it's cheap insurance
Inspect transmission cooler lines and mount annually on ZR2s that see trails — catching these early prevents bigger damage
Diesel owners should use premium fuel additives and change fuel filter every 15k to prevent injector failures downstream
The V6 ZR2 is a solid buy if transmission history is clean; avoid the 2.8L diesel entirely unless you can absorb a $10k+ engine replacement risk.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: AGM battery required for vehicles with start-stop technology
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Every control module on the 2021-2023 Chevrolet Colorado ZR2 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Fuel Pump Control Module (FPCM)0.8 hr R&Rno coding3.6L V6 and 2.7L turbo I4 gasoline only▸ programming details
📍 Left frame rail below driver door, near fuel tank
⚠️ Diesel models do not use FPCM; fuel system controlled directly by ECM
Driver Information Center (DIC)0.8 hr R&Rsecurity gateway +0.8 hr
📍 Integrated with instrument cluster module
🔧 GM SPS2 / ACDelco TDS with SGW unlock
⚠️ Not a separate module; functionality integrated with IPC. Listed for reference only
Headlamp Control Module (HCM)0.6 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Behind left headlamp assembly in engine bay
🔧 GM Tech 2 or aftermarket scan tool
⚠️ Controls automatic headlamps, DRL, fog lamps. LED headlamps standard 2021+
Rear Vision Camera Module (RVCM)0.5 hr R&Rno coding
📍 Integrated with tailgate handle camera assembly
⚠️ Standard equipment. Camera calibration not required; plug-and-play replacement
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
General Motors, LLC (GM) is recalling certain 2020 Chevrolet Bolt EV and 2021 GMC Canyon and Sierra 1500, 2500 and 3500, Yukon, Yukon XL, Cadillac Escalade and Escalade ESV and Chevrolet Blazer, Camaro, Colorado, Equinox, Silverado 1500, 2500 and 3500, Suburban and Tahoe vehicles. Incorrect bolts may have been used at one or more fastening locations to secure the seat belts to the vehicle. If an incorrect bolt was used, the seat belt may not be properly attached to the vehicle.
Consequence: If a seat belt assembly is not properly attached to the vehicle, the seat belt may not properly restrain an occupant in the event of a crash, increasing the risk of injury.
Remedy: GM will notify owners, and dealers will replace the suspect bolts, free of charge. The recall began January 29, 2021. Owners may contact GMC customer service at 1-800-462-8785, Cadillac customer service at 1-800-458-8006, or Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N202322230.
Performance
Horsepower
308hp
Torque
275lb-ft
0–60 mph
7.0sec
Quarter mile
15.3sec
Top speed
100mph
Fuel economy (EPA)
City
16mpg
Highway
18mpg
Combined
17mpg
Fuel
Regular Gasoline
Capability & size
Towing capacity
5,000lb
Payload
1,100lb
Curb weight
4,850lb
EPA class
Small Pickup Trucks 4WD
Wiper blades
ZR2 off-road trim uses same wiper specs as base Colorado (second gen). Pickup trucks do not have rear wipers.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2021 Chevrolet Colorado ZR2 3.6L V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Mechanic · 20+ years.