Engine Camshaft Position Sensor for the 1999-2007 GMC Sierra 1500
A bad camshaft sensor can cause stalling or a no-start in your Sierra; learn how to choose the right replacement.
- A failing sensor can cause serious issues like engine stalling, hard starting, or a no-start condition.
- On V8 models, the sensor is at the back of the engine behind the intake manifold and is difficult to access but can be replaced by a patient DIYer.
- For this critical sensor, it is highly recommended to use an OEM brand like ACDelco or a top-tier aftermarket brand like Delphi for reliability.
- Common trouble codes associated with this failure include P0340, P0341, and P0342.
Is Your Sierra Stalling or Running Rough? It Could Be the Camshaft Sensor
If you own a 1999-2007 GMC Sierra 1500, you have a tough, reliable truck. But as these GMT800 pickups age, certain electronic parts start to wear out. The camshaft position sensor is a common failure item that can cause frustrating problems. Because it provides vital information for engine timing, a bad sensor can make your truck run poorly, or even leave you stranded. Understanding the symptoms and knowing how to choose a quality replacement part is key to getting your Sierra back on the road.
Critical Part Warning
A failing camshaft position sensor can cause your engine to stall unexpectedly while driving. While the truck may restart, the risk of stalling in traffic makes this a serious safety issue that should be addressed promptly.
Signs of a Failing Camshaft Position Sensor
A bad cam sensor will usually let you know something is wrong. The most common signs include:
- Check Engine Light: This is often the first sign. You may see codes like P0340, P0341, or P0342 stored in the computer.
- Hard Starting: The engine may crank for a long time before it finally starts. In some cases, it might not start at all.
- Engine Stalling: The engine may suddenly shut off while idling or driving. This can be intermittent, often happening after the engine has warmed up.
- Rough Idle and Misfires: Your truck may shake or vibrate at a stop, and you might feel the engine stumbling.
- Poor Acceleration: A lack of power when you press the gas pedal is a common complaint.
Choosing the Right Aftermarket Sensor: Brand Matters
When it comes to critical electronic sensors, not all aftermarket brands are created equal. For this specific part on your Sierra, owner forums and experienced mechanics often recommend sticking with brands known for their quality and reliability. While a cheaper part might be tempting, it could fail prematurely, forcing you to do the job all over again.
Here’s a breakdown of available brands into tiers:
- Tier 1 (OEM Quality): ACDelco and Delphi. ACDelco is the original equipment manufacturer for GM. Choosing either of these brands is the closest you can get to buying the part from a GM dealer. They are highly recommended for fit and long-term reliability.
- Tier 2 (High-Quality Aftermarket): Brands like Standard Ignition (SMP), NGK, Hitachi, and Walker Products have a solid reputation for producing reliable engine management parts. These are a good alternative if OEM-level parts aren't in the budget.
- Tier 3 (Economy): This category includes many other brands. While the price is low, the quality can be inconsistent. Given the sensor's difficult-to-reach location on V8 models, saving a few dollars on the part might not be worth the risk of an early failure and repeated labor.
Pro Tip: Check the Crankshaft Sensor Too
The camshaft sensor works with the crankshaft position sensor. While there were no major recalls for the cam sensor on these trucks, there was a recall for the crankshaft position sensor on some 2001 models with the 8.1L V8 engine (NHTSA Recall 07V-521). The symptoms are very similar. If you are replacing one, it's wise to inspect the other, especially its wiring and connector.
🎬 Check out this guide for replacing the related crankshaft position sensor.How Much Does a Replacement Cost?
The cost depends on whether you do it yourself or have a shop do the work. The part itself is not expensive, but labor can add up due to its location.
| Part or Service | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $24 - $75 |
| New OEM (ACDelco) Sensor | $50 - $90 |
| Shop Labor | $100 - $175 |
| Total (Shop Repair) | $124 - $265 |
Frequently Asked Questions
Where is the camshaft position sensor on my 1999-2007 Sierra?
For the common V8 engines (4.8L, 5.3L, 6.0L), the sensor is located on the top of the engine block, at the very back, behind the intake manifold. It is held in by a single 10mm bolt. For the 4.3L V6, it is located underneath the distributor cap.
🎬 See how to replace the sensor on a 4.3L V6 engine.Can I replace this sensor myself?
Yes, this is a DIY-friendly job if you have patience. 🎬 Watch this step-by-step walkthrough for replacing the sensor on V8 models. On V8 models, access is very tight. You will be working by feel. You'll need a ratchet with a long extension and a 10mm socket. While you don't have to remove the intake manifold, some people find it easier to do so for better access.
What happens if I ignore a bad camshaft sensor?
Ignoring it can lead to more than just poor performance. Your truck could stall in a dangerous situation, such as in the middle of an intersection. It can also lead to a no-start condition, leaving you stranded without warning. It won't typically cause catastrophic engine damage, but the safety risks are significant.
Is the camshaft sensor the same as the crankshaft sensor?
No, they are two different sensors, though they have similar symptoms when they fail. The camshaft sensor tracks the position of the camshaft (which controls the valves), while the crankshaft sensor tracks the position of the crankshaft (which is connected to the pistons). The computer uses signals from both to run the engine correctly.
Helpful Videos
Technical Specifications
OEM Part Numbers: 19420911 12561211 19420372
Single bolt-on sensor with an integrated electrical connector. On V8 models, it is located at the top rear of the engine block. On V6 models, it is located inside the distributor.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- GMC Sierra 1500:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your Sierra Stalling or Running Rough? It Could Be the Camshaft Sensor
- Critical Part Warning
- Signs of a Failing Camshaft Position Sensor
- Choosing the Right Aftermarket Sensor: Brand Matters
- Pro Tip: Check the Crankshaft Sensor Too
- How Much Does a Replacement Cost?
- Frequently Asked Questions
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