A Chevrolet VIN decodes the same way as any modern VIN: positions 1-3 are GM's manufacturer code (1G1 is a US-built Chevy car, 1GC a Chevy truck, 2G1 a Canada-built car, 3GN a Mexico-built SUV), positions 4-8 cover line, body, drive, and engine, position 9 is the check digit, 10 is the year, and 11 is the plant. The VIN does not list every option, though. For that you read the RPO codes on the glovebox SPID label or, on most 2018 and newer GM vehicles, the QR code on the door-pillar label. Then you run a history report.
We are writing this in mid October 2026, and the Chevy listings we see most often are Silverados, Tahoes, Equinoxes, and the odd Malibu, usually with a seller claim like "Z71, max tow, 6.2." Some of those claims are true. Some are a 5.3 with stickers. A VIN decode plus the RPO list sorts that out in about ten minutes, and a report covers what happened after the truck left the plant. For the general version of this, see our guide on how to decode a VIN.
Positions 1-3: GM prefixes mostly tell you country and type
The WMI identifies the maker, and with GM the useful part is country plus vehicle type. When we ran the common prefixes through NHTSA's vPIC decoder, every one came back as General Motors LLC. 1G1 and 2G1 and 3G1 are passenger cars (US, Canada, Mexico). 1GC and 3GC are trucks, which covers Silverado and Colorado. 1GN, 2GN, and 3GN are multipurpose vehicles, so Tahoe, Suburban, Traverse, Equinox, and friends. KL7 is a GM SUV prefix from South Korea, which you see on vehicles like the Trax. GMC trucks start 1GT, and Cadillac cars start 1G6.
So a 3GN on a Chevy SUV is normal. It means Mexico-built, and our test Equinox pattern decoded to Ramos Arizpe, Coahuila. A 1GC on something the seller calls an Equinox is a problem.
Positions 4-8: GM's descriptor and the engine letter
The vehicle descriptor section holds line, series, body, drive, restraint details, and the engine, and GM changes the layout between generations. Federal rules in 49 CFR Part 565 require the content, not a shared alphabet. In our tests, a 2020-pattern 1GCUYDED returned a Silverado 1500 LT, 4WD, 5.3-liter, engine L84. A 2015-pattern 1GCVKREC returned a Silverado 1500 LT, 4WD, 5.3-liter, engine L83. Same displacement, different engine, and the eighth character is the engine letter (D on the newer truck, C on the older one). That L84 and L83 label is an RPO code, which is where GM decoding gets more useful than most brands.
Position 9 is the check digit. Every other character is converted to a number and weighted, the total is divided by 11, and the remainder (or X for 10) has to match. A failed check digit on a listing usually means a typo. On a title, it means stop.
Positions 10-17: year, plant, serial
Position 10 is the model year: L for 2020, M for 2021, N for 2022, P for 2023, R for 2024, S for 2025, T for 2026. Position 11 is the assembly plant. In our decodes, Z came back as GM's Fort Wayne truck plant in Indiana (vPIC labels the city Fort Wayne on one year and Roanoke on another), F as Kansas City, Kansas on a Malibu, S as Ramos Arizpe, and 1 as Oshawa, Ontario on an Impala. Positions 12-17 are the serial. Compare all 17 characters on the dash, the door label, and the title. Our page on finding and verifying a VIN covers the extra spots.
RPO codes: the SPID label and the 2018 QR code
GM's Regular Production Option codes are three-character codes for factory equipment, and they fill in what the VIN skips: axle ratio, trailering packages, paint, trim, suspension, and more. On older GM vehicles they print on the Service Parts Identification (SPID) label, usually inside the glovebox. GM's service bulletin 17-NA-213 says that for 2018 model year vehicles the SPID label was being discontinued and much of its content moved into a QR code on the certification label on the driver-side B-pillar, phased in over several months. If there is no QR code, the bulletin says the SPID label is in its usual spot. Scan the QR with a phone and you get the VIN, model year, model, build date, the RPO list, and the paint code.
Look, this is the part sellers do not expect you to check. If the listing says Z71 and Z71 is not in the RPO list, you have a question to ask. If the RPO list shows a different paint code than the paint on the truck, ask about the respray. And if the VIN and the SPID or QR data name different vehicles, walk away.
Why the history check still matters
RPO codes also decide recall coverage, which is a good reason to run both a decode and a VIN-specific recall check. GM's May 2025 recall report 25V274 covers about 597,571 2021-2024 trucks and SUVs with the 6.2-liter V8, RPO L87, built in a suspect window, for engine failure that can cause loss of propulsion. In January 2026 NHTSA opened a recall query into failures reported after the remedy. Check the exact VIN on GM's recall lookup, then compare it against the report, per our NHTSA recall vs CARFAX guide. Shopping diesel? Read Duramax used truck history too.
The decode will not show a salvage auction, a flood claim, or a rolled cluster. Get your own report and skip the seller's PDF, since fake CARFAX reports still show up on truck listings. As of mid October 2026, a CARFAX report through us is about $5.50 as a guest or $4.50 as a member, and the CARFAX plus AutoCheck bundle is about $6.75, versus roughly $39.99 to $44.99 retail. Confirm at checkout. We are a licensed CARFAX and AutoCheck reseller, not affiliated with CARFAX, AutoCheck, or Experian.
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