GM Atlas Vortec 2.8L LK5: Specs, Engine Codes, Controllers & Maintenance
Engine Information · GM · Atlas · original four-cylinder
Atlas Vortec 2.8L LK5
The LK5 is the four-cylinder member of GM’s modular Atlas family. It combines an aluminum DOHC engine with port injection and exhaust cam phasing, powering the early Canyon and Colorado without a turbocharger.
Engine construction
| Specification | Details |
|---|---|
| Capacity / layout | 2.8L · inline-four |
| Construction | Aluminum block and head |
| Valve gear | DOHC · 16 valves · exhaust cam phasing |
| Fuel / induction | Sequential port injection · naturally aspirated |
| Timing drive | Chain |
Codes & output
| RPO / version | Power / torque | Key difference |
|---|---|---|
| LK5 | 175 hp / 185 lb-ft | Canyon / Colorado |
SAE horsepower; torque in lb-ft. Ratings are for the stated application and fuel, rather than every vehicle with this RPO.
Vehicles & model years
| Brand | Model | Model years | Platform / chassis | Engine RPO |
|---|---|---|---|---|
| GMC / Chevrolet | Canyon / Colorado | 2005–2006 in this coverage | GMT355 | LK5 |
U.S. and Canadian applications within the 2005–2026 matrix scope. Engine availability depends on trim, build date and emissions certification.
Engine controllers
| Application / revision | ECM or PCM | Identification & function |
|---|---|---|
| LK5 | GM P12 PCM | Fuel, ignition, throttle, cam phasing and automatic-transmission functions where equipped |
| Parts / programming | RPO and PCM service ID required | Do not select a file from the similar-looking larger Atlas engines |
Identify the module from its service number, operating-system ID and VIN. The ECM/PCM and transmission controller have separate calibrations on many applications; a matching RPO alone does not make a replacement module plug-and-play.
Common issues & maintenance
- Early intake-valve seat wearGM documented intake-valve leakage on selected 2004–2006 LK5/L52 trucks. A persistent misfire with low compression needs a leak-down test and cylinder-head inspection; ignition parts will not repair a leaking valve.
- Cam timing / oil controlP0014/P0017 or a rough idle can involve the cam-actuator solenoid and its screens. GM also calls for crankshaft end-play checks when ordinary diagnosis does not explain the condition; do not assume a chain is at fault from the code alone.
- Ignition and air leaksCoils, worn plugs and intake leaks can cause rough running. Use cylinder misfire counts and fuel trims to separate ignition faults from mechanical compression loss.
Keep it healthy. Use the correct oil grade and keep the level full; cam phasing depends on oil delivery. Follow plug, coolant and filter schedules. Persistent misfires need compression and leak-down tests before repeated parts replacement.
References & technical sources
| Source | Reference |
|---|---|
| GM applications & RPO diagnostic matrices | View source |
| EFILive GM gasoline controller families | View source |
| EFILive production controller database | View source |
| GM Atlas cam-actuator diagnostic bulletin | View source |
| GM 07123A intake-valve guidance | View source |
| GMC 2005 Canyon owner manual | View source |
