A Pontiac G8 Owner's Guide to the Engine Crankshaft Position Sensor (2008-2009)
If your G8 is stalling or won't start, the crankshaft position sensor is a likely suspect.
- On V8 models, the sensor is very difficult to access; the starter motor must be removed.
- A "Crankshaft Variation Relearn" procedure with a professional scan tool is mandatory after replacement.
- Due to the high labor cost, using a top-tier brand like ACDelco or Delphi is strongly recommended to avoid repeat failures.
- Symptoms like stalling and no-start are common, making a faulty sensor a safety concern.
Is Your Pontiac G8 Stalling or Hard to Start?
A failing crankshaft position sensor is a common problem that can leave you stranded. When this sensor starts to go bad, it sends weak or incorrect signals to your car's computer. This can cause a variety of frustrating engine problems, from a simple Check Engine Light to the engine shutting off while you're driving. G8 owners have reported issues like the engine cranking but not starting, or stalling when the car is hot.
Symptoms of a Failing Crankshaft Position Sensor
- Engine Cranks but Won't Start: The computer doesn't have the information it needs to start the engine.
- Sudden Stalling: The engine may shut off unexpectedly while driving, which can be very dangerous.
- Check Engine Light: The most common codes triggered are P0335 and P0336. 🎬 See how to diagnose persistent P0335 and P0336 codes.
- Rough Idle and Misfires: The engine may shake, run poorly, and you might feel a loss of power.
- Poor Acceleration: Your G8 may feel sluggish and not respond quickly when you press the gas pedal.
- Reduced Fuel Economy: Incorrect timing for fuel and spark means your engine isn't running efficiently.
Installation Warning: Location and Labor
Replacing this sensor is not a simple job, especially on the V8 models (GT and GXP). The sensor is located on the lower passenger side of the engine block, right above the starter motor. 🎬 Watch this walkthrough of the sensor replacement process. To access it, the starter must be removed. If you have aftermarket headers, the job becomes even more difficult, as the header may need to be loosened or removed to get the starter out. This is a challenging job for a DIY mechanic and can lead to 2-3 hours of shop labor costs.
Choosing the Right Aftermarket Sensor
For a part this critical and difficult to replace, quality matters. You don't want to do this job twice. Here’s a breakdown of available brands.
Tier 1: OEM-Grade Brands
These brands are either the original equipment manufacturer or have a reputation for meeting or exceeding OEM standards. For a critical sensor like this, sticking to this tier is highly recommended.
- ACDelco: This is the original GM parts brand. It's the factory part your G8 came with and offers the best guarantee of fit and performance.
- Delphi: Delphi was a part of General Motors and is a major OEM supplier for sensors and electronics. Their parts are widely considered to be of the same quality as ACDelco.
Tier 2: Reputable Aftermarket Brands
These brands are known for producing quality components and are a solid choice if OEM-grade parts aren't available.
- Bosch: A well-respected German company known for high-quality electronics.
- NGK/NTK: Known for their ignition components, NTK is their sensor line and is well-regarded.
- Standard Motor Products (SMP): A long-standing aftermarket company that produces reliable sensors.
Tier 3: Value Brands
These brands offer the lowest price but can be a gamble on quality and longevity. Given the high labor cost to replace this sensor, saving a few dollars on the part itself is generally not worth the risk.
- Dorman, Spectra, Walker Products, and various store brands fall into this category.
CRITICAL STEP: Crankshaft Variation Relearn Procedure
After replacing the crankshaft position sensor on any 2008-2009 Pontiac G8, you MUST perform a "Crankshaft Position Variation Learn" procedure (also called a CASE relearn). The engine computer needs to be calibrated to the new sensor. If you skip this step, the car may continue to run poorly, misfire, and will likely keep the P1336 trouble code stored. This procedure requires a GM Tech 2 or a high-end professional scan tool that has this specific function. A standard, inexpensive code reader cannot perform this function.
🎬 Watch a professional demonstration of the CASE relearn procedure.Frequently Asked Questions
Where is the crankshaft position sensor located on the Pontiac G8?
On the V8 models (G8 GT, G8 GXP), the sensor is on the passenger side of the engine block, tucked away behind the starter motor. On the V6 model, the location is different but generally more accessible.
Can I replace this sensor myself?
For V8 owners, this is a difficult DIY job due to the location. It requires removing the starter, which can be very challenging, especially with aftermarket exhaust headers. You also need a professional-grade scan tool to perform the mandatory relearn procedure afterward. For most owners, professional installation is recommended.
What is a "crank relearn" and is it really necessary?
A crank relearn, or CASE learn, calibrates the engine computer to the precise signal of the new crankshaft sensor. It is absolutely necessary on these GM vehicles. Without it, the computer can't accurately read engine timing, leading to rough running, misfires, and a persistent Check Engine Light with code P1336.
Are there any recalls for the G8 crankshaft sensor?
No. While the 2008-2009 Pontiac G8 has had a few safety recalls, none of them are related to the crankshaft position sensor.
Helpful Videos
Technical Specifications
OEM Part Numbers: 12703627 12585546 213-3520
For V8 models (6.0L L76, 6.2L LS3), this is a 3-pin sensor designed for a 58x crankshaft reluctor wheel. V6 models use a different part.
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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.
- Pontiac G8:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your Pontiac G8 Stalling or Hard to Start?
- Symptoms of a Failing Crankshaft Position Sensor
- Installation Warning: Location and Labor
- Choosing the Right Aftermarket Sensor
- CRITICAL STEP: Crankshaft Variation Relearn Procedure
- Frequently Asked Questions
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