GMC Envoy Camshaft Position Sensor Guide for 2002-2009 Models
Fix stalling, rough idling, and starting problems in your Envoy by understanding and choosing the right camshaft position sensor.
- A failing camshaft position sensor on your Envoy will most likely trigger a P0340 check engine light code and cause stalling, hard starting, or a rough idle.
- For the common 4.2L engine, this is a very easy DIY repair that takes less than 30 minutes and only requires a 10mm wrench.
- For critical electronics like this, choosing a quality OEM (ACDelco) or premium aftermarket (Delphi, NTK) brand is highly recommended to avoid premature failure.
- Do not confuse the sensor with the nearby camshaft actuator solenoid, which causes similar symptoms but different trouble codes.
Is Your GMC Envoy Stalling or Hard to Start?
If you're dealing with a Check Engine Light and your 2002-2009 Envoy is running poorly, a bad camshaft position sensor is a very common cause. When this small electronic part fails, it can't tell the engine's computer where the camshaft is, leading to a host of frustrating and potentially serious engine problems. Luckily, for the popular 4.2L inline-6 engine, this is an inexpensive part that is very easy to replace yourself.
Symptoms of a Failing Camshaft Position Sensor
When the sensor starts to go bad, it sends a weak, incorrect, or no signal to the engine computer. This leaves the computer guessing, which leads to noticeable performance issues. Here are the most common signs:
- Check Engine Light: This is usually the first warning. A code scan will almost always show P0340, which points directly to a fault in the 🎬 Watch this guide on how to fix the P0340 code. camshaft position sensor circuit.
- Engine Won't Start: The engine will crank over but may refuse to start. This happens because the computer doesn't have the information it needs to time the spark and fuel.
- Hard Starting: You might have to crank the engine for a long time before it finally sputters and starts.
- Engine Stalling: The engine can suddenly shut off while you're driving or when you're stopped at a light. This can be a serious safety risk.
- Rough Idle and Misfires: Your Envoy may shake or vibrate while idling. The engine might sound like it's sputtering or running unevenly.
- Poor Acceleration: With the timing off, the engine can't produce full power, making the truck feel sluggish and slow to accelerate.
A Note on a Related Part: The Camshaft Actuator Solenoid
The camshaft position sensor is often confused with the Camshaft Position Actuator Solenoid (also called a VVT solenoid). This part is located very close to the sensor on the 4.2L engine and can cause similar issues like rough idle. However, the actuator solenoid will typically trigger different codes, such as P0013 or P0014. Always use a code scanner to confirm which part has failed.
🎬 See how to replace the VVT solenoid on the 4.2L engine.Choosing the Right Aftermarket Sensor for Your Envoy
When it comes to electronic sensors, quality matters. While many budget-friendly options exist, a cheap sensor that fails early will mean you have to do the job all over again. Here’s how to think about your options:
- OEM (Original Equipment Manufacturer): ACDelco is the original GM parts brand. Choosing a "GM Genuine" or ACDelco part guarantees the same quality that your Envoy was built with.
- Premium Aftermarket: Brands like Delphi, Standard Motor Products (SMP), and NTK are well-regarded in the industry. Delphi was once part of GM and is considered an OEM-quality alternative. These brands provide excellent reliability at a price often lower than the dealer.
- Value Aftermarket (Replacement Brand): This tier includes various brands that focus on affordability. While the initial cost saving is attractive, the long-term reliability of these sensors can be inconsistent for GM vehicles. Given how easy this part is to change on the 4.2L engine, some owners may choose this option, but for critical sensors, spending a little more for a premium brand is often a wise investment.
Pro Tip: For the 4.2L engine, the replacement job takes less than 30 minutes. Because the labor is so simple, it makes sense to invest in a higher-quality part to ensure you won't be dealing with the same problem again in a year.
Cost of Replacing the Camshaft Position Sensor (2002-2009 GMC Envoy)
| Part/Service | Estimated Cost |
|---|---|
| New OEM (ACDelco) Part | $30 - $50 |
| New Aftermarket Part | $25 - $40 |
| Shop Labor (4.2L Engine) | $50 - $120 |
| Total Professional Replacement | $75 - $170 |
| Total DIY Replacement | $25 - $50 (Cost of Part) |
Frequently Asked Questions
Where is the camshaft position sensor located on the GMC Envoy?
For the 4.2L inline-6 engine, the sensor is on the front of the engine on the driver's side. It's near the oil fill cap and the power steering pump, mounted to the cylinder head with a single bolt. For the optional 5.3L V8 engine, the sensor is much harder to access. It is located at the very back of the engine block, near the firewall and behind the intake manifold.
Can I replace this sensor myself?
Yes, for the 4.2L engine, this is a great DIY job for beginners. It is very easy to access and requires only a 10mm socket or wrench. 🎬 Follow this walkthrough to locate and replace your sensor. The entire job can be done in under 30 minutes. However, replacement on the 5.3L V8 is much more difficult and may require removing the intake manifold, which is best left to an experienced mechanic.
Are there any recalls for the camshaft position sensor on the Envoy?
No, there are no specific recalls from GM or the NHTSA for the camshaft position sensor on the 2002-2009 GMC Envoy. While other recalls exist for this vehicle, they do not pertain to this part.
What happens if I don't replace a bad sensor?
Ignoring a failing sensor is not recommended. Your Envoy will continue to run poorly, get bad gas mileage, and could stall unexpectedly, which is a major safety hazard. If the sensor fails completely, you could be left stranded with a vehicle that will not start. Continuing to drive with a misfire can also damage your expensive catalytic converter over time.
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Technical Specifications
OEM Part Numbers: 12684186 213-4223 12608424 12674704
For the 4.2L I6 engine, the sensor is located on the driver's side of the cylinder head and is held in by one 10mm bolt. It uses a 3-prong electrical connector.
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.
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