Engine Crankshaft Position Sensor Guide for the 2007-2011 GMC Sierra
Solve stalling, rough idle, and no-start problems on your Sierra by understanding this critical sensor.
- A failing sensor causes serious issues like stalling, no-starts, and rough running; do not ignore these symptoms.
- Replacement requires removing the starter motor to access the sensor, which is located on the passenger side of the engine block.
- A 'CASE relearn' procedure with a proper scan tool is mandatory after installation to avoid a check engine light and performance problems.
- Consider spending more on an OEM (ACDelco) or reputable aftermarket brand (Delphi, NGK) to avoid premature failure and repeating the labor-intensive installation.
Is Your Sierra Stalling or Running Rough? It Could Be the Crankshaft Sensor.
If your 2007-2011 GMC Sierra is suddenly hard to start, stalling at red lights, or running rough, a failing crankshaft position sensor is a common suspect. This sensor provides the engine's main computer with the information it needs to manage engine timing and fuel delivery. When it fails, the computer is essentially flying blind, which can cause significant and sometimes dangerous driving problems. Ignoring the signs can lead to getting stranded or even potential engine damage.
🎬 Watch: Common symptoms of a failing crankshaft position sensorChoosing the Right Aftermarket Crankshaft Sensor
When replacing a critical sensor like this, part quality matters. While many aftermarket options are available, they are not all created equal. For a part that can leave you stranded, choosing a reliable brand is key.
Aftermarket Brand Quality Tiers
| Tier | Brands | Notes |
|---|---|---|
| 🏆 Top Tier (OEM or Equivalent) | ACDelco GM Genuine, Delphi, NGK/NTK | These brands are often the original equipment manufacturers for GM. They offer the highest likelihood of a perfect fit and long-term reliability. While ACDelco is the OEM brand, be aware they offer different lines; 'GM Genuine' is the top choice. |
| ✅ Mid-Grade (Reliable Aftermarket) | Standard Ignition (SMP), Walker Products | Standard Motor Products is a well-regarded aftermarket manufacturer. These brands offer a good balance of quality and price and are a solid choice for most owners. |
| ⚠️ Economy (Use with Caution) | Dorman, Global Parts, True Tech, Store Brands | While attractively priced, economy sensors have a higher reported failure rate. They might work in a pinch, but for a critical sensor that requires significant labor to replace, it's often worth spending more for a better part to avoid doing the job twice. |
Known Issues for 2007-2011 GMC Sierra
TSB 17-NA-317: Wiring Harness Interference
General Motors issued a Technical Service Bulletin for some trucks that experience issues like stalling, reduced engine power, or a transmission that slips out of gear. The bulletin states that the crankshaft position sensor circuit can pick up electrical interference from other wires in the same harness. The official fix is to install a special twisted-pair jumper harness to shield the sensor's signal. If you replace your sensor and still have intermittent issues, this TSB could be the reason.
Installation Tips
On the V8 engines common in the 2007-2011 Sierra (4.8L, 5.3L, 6.0L, 6.2L), the crankshaft position sensor is located on the lower passenger side of the engine block, just above the starter. Unfortunately, this means you must remove the starter to gain access. The sensor itself is held in by a single 10mm bolt.
🎬 See this step-by-step walkthrough for removing the starter and sensorCrankshaft Variation Relearn Procedure: After replacing the sensor, your truck requires a "crankshaft variation relearn" or "CASE relearn." This procedure must be done with a compatible OBD-II scan tool. Skipping this step will likely result in a persistent Check Engine Light and may cause the engine to run poorly. Most repair shops can perform this service.
🎬 Watch: How to perform the mandatory crankshaft variation relearn procedureFrequently Asked Questions (FAQ)
Can I drive my Sierra with a bad crankshaft position sensor?
It is not recommended. A failing sensor can cause the engine to stall at any time, which is a major safety risk, especially at high speeds or in traffic. If the sensor fails completely, the engine will not start at all, leaving you stranded.
What's the difference between a crankshaft and camshaft sensor?
They perform similar functions but monitor different shafts. The crankshaft sensor tracks the position of the crankshaft (and pistons), while the camshaft sensor tracks the position of the camshaft (and valves). Both are critical for engine timing, and sometimes a failure in one can mimic a failure in the other.
Why is my check engine light still on after replacing the sensor?
There are a few common reasons. First, the diagnostic trouble codes must be cleared with a scan tool. Second, the mandatory crankshaft variation relearn procedure must be performed. If both of those have been done, you could have a wiring issue (like the one described in TSB 17-NA-317), a faulty new sensor, or a problem with another component.
Do I need to replace the wiring harness too?
Not always, but you should inspect the connector and wiring for any signs of damage, melting, or corrosion. The pigtail connector can become brittle from heat cycles. Given the TSB regarding electrical interference, if you continue to have problems, the jumper harness might be necessary.
Helpful Videos
Technical Specifications
OEM Part Numbers: 12585546 12703627 12595966
Location: Lower passenger side of engine block, above starter. Retaining Bolt Size: 10mm. Connector: 3-pin oval connector. A CASE relearn procedure is required after replacement.
We Have This Part in Stock
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: