Camshaft Position Sensor & Gears

There are three camshaft gears and three camshaft sensors available for your engine. These parts do not interchange and must be replaced with the same year parts or the engine will not work properly. The 2001 camshaft gear / sprocket and camshaft timing position sensor were revised in 2002 and again in 2004 to maximize the benefits of Magnetic Reluctance (MR) or “mirror image” ignition timing. To “read” the new changes, the cam sensor also had to be updated to match both the newer 2002-2003 and 2004+ camshaft gear.

8.1L / 496cid Timing Set Swap Information

Please note: We do not sell timing gears or camshaft position sensors.

The camshaft position sensor on your engine will only work with the corresponding cam gear from the same year. To swap sprockets or sensors, you must swap both the camshaft timing gear and camshaft position sensor. In the case of the latest model (2004+) timing sets, you will also need to purchase the new "tall sensor" timing cover and conversion harness. The stock computer will run all three units without modification or tuning required.

vortec 8100 8.1L 496 2001 camshaft gear cam position sensor

2001 engines use a discontinued camshaft gear and sensor. The early model sensor and gear were replaced by the more accurate 2002-2003 model.
The 2001 engines swap with the 2002-2003 gear and sensor without requiring the 2004+ pigtail and "tall sensor" timing cover. To swap to 2004+, the timing cover must also be changed to fit the taller sensor.

  • Camshaft Position Sensor GM 12575182
    (discontinued part, can sometimes be found online)
vortec 8100 8.1L 496 2002 2003 camshaft gear cam position sensor

2002-2003 engines use a slightly different camshaft gear and sensor calibrated to the alternating grooves within the gear.

  • Camshaft Position Sensor GM 12575183
vortec 8100 8.1L 496 2004 and up camshaft gear cam position sensor

2004 and newer engines use the "tall sensor" and corresponding timing cover. The camshaft position sensor also has a different configuration and requires a pigtail to convert earlier engine harnesses.

  • Camshaft Position Sensor GM 12591720
  • Sensor Adapter Pigtail Standard HP4240
    (for early model engine conversions)

Early Timing Cover Vs. Tall 04+ Cover

vortec 8100 8.1L 496 timing cover comparison

The 2001-2003 engines use a different timing cover than the later model 2004+ engines. The 2004+ timing cover was changed to accommodate the taller sensor design and does not work with 2001 or 2002-2003 camshaft position sensors. If swapping to the 2004+ gear and sensor combination, you must also change your timing cover.

8.1L Camshaft Position Sensor Guide

vortec 8100 8.1L 496 camshaft position sensor differences

There are three application specific camshaft position sensors available for the 8.1L Vortec engine.

  • 2001 - GM 12575182
  • 2002-2003 - GM 12575183
  • 2004+ - GM 12591720

The 2001 and 2002-2003 camshaft position sensor plugs are wired differently than the later model 2004+ sensor and require a pigtail adapter to complete the swap. The 2004+ sensor also has a longer magnetic reader that fits inside the timing cover, requiring the later model 2004+ timing cover with the raised sensor section to fit the added length.

  • Sensor Adapter Pigtail Standard HP4240
  • 2001 / 2002-2003 Timing Cover GM 12566113
  • 2004+ Tall Sensor Timing Cover GM 12589846