Ram 2500 Ignition Knock (Detonation) Sensor Guide for Hemi Engines (2011-2022)
Don't let a bad knock sensor hurt your Hemi's performance or cause engine damage.
- This part is for Hemi V8 engines only, not the 6.7L Cummins diesel.
- Your Ram 2500 has two knock sensors; consider replacing them in pairs on high-mileage vehicles.
- Using OEM (Mopar), NGK/NTK, or Delphi parts is highly recommended to avoid repeat failures.
- Always torque the new sensor to the correct specification (15 ft-lbs) and inspect the wiring harness for damage.
Is Your Ram 2500 Knock Sensor Failing?
A failing knock sensor won't leave your truck stranded, but it shouldn't be ignored. The most common sign is a Check Engine Light on your dashboard. When you scan the code, you'll likely see P0325 (for sensor 1) or P0330 (for sensor 2). You might also notice your truck feels sluggish, hesitates when you accelerate, and gets worse fuel mileage. In some cases, you may hear a faint pinging or knocking sound during acceleration, which is the very thing the sensor is supposed to prevent.
🎬 Watch: How to identify symptoms and test for a bad sensorChoosing the Right Aftermarket Knock Sensor for Your Hemi
When it comes to electronic sensors on Ram trucks, not all parts are created equal. The engine computer is sensitive and expects signals that fall within specific ranges. While many aftermarket options are available, owner forums often highlight that choosing the wrong brand can lead to the check engine light returning shortly after the repair.
A Note on Cummins vs. Hemi
This guide is for the 5.7L and 6.4L Hemi V8 gasoline engines only. The 6.7L Cummins diesel engine is a compression-ignition engine and does not use ignition knock sensors. The sensors in the Cummins exhaust system are NOx sensors, which serve a completely different emissions-related function.
Brand Quality Tiers
- Top Tier (OEM & OE-Equivalent): For maximum peace of mind, Mopar (the OEM part) is the safest choice. Brands like NGK (also sold as NTK) and Delphi are often the original equipment manufacturers for many automakers and are widely trusted to perform identically to the factory part. They are an excellent balance of quality and price.
- Mid Tier (Trusted Aftermarket): Brands like Standard Ignition and Beck Arnley have a long history of producing reliable aftermarket components. They offer a good value and are a solid choice for many repairs.
- Economy Tier (Budget-Focused): Brands like Holstein, Walker Products, and others offer a cost-effective solution. While they can get the job done, it's important to be aware that with sensitive electronics, the risk of an out-of-spec part is slightly higher. Check warranty information before purchasing.
Cost to Replace a Ram 2500 Knock Sensor
The total cost depends on whether you do the job yourself or hire a professional. Your Ram 2500 Hemi has two knock sensors. While you only need to replace the one that has failed, it's often wise to replace them in pairs, especially on higher-mileage trucks, as the labor to access them is the same.
| Part/Service | Estimated Cost |
|---|---|
| New OEM (Mopar) Sensor (x1) | $70 - $130 |
| New Aftermarket Sensor (x1) | $21 - $86 |
| Shop Labor | $100 - $200 |
| Total DIY (1 Aftermarket Sensor) | $21 - $86 |
| Total Shop Visit (1 OEM Sensor) | $170 - $330 |
Pro Tip: Check the Harness and Torque
Before you replace the sensor, inspect its wiring connector. The heat from the exhaust manifold can make the plastic brittle, causing it to crack or the wires to fray. Sometimes, the harness is the real problem. Also, knock sensors are very sensitive to how tight they are installed. The correct torque for the mounting bolt on Hemi engines is 15 ft-lbs. Over-tightening can damage the sensor, and under-tightening can lead to false signals.
🎬 See this video for sensor locations and proper torque specsFrequently Asked Questions
How many knock sensors does my 2011-2022 Ram 2500 have?
If you have a 5.7L or 6.4L Hemi V8 engine, your truck has two knock sensors. One is for Bank 1 (passenger side) and the other is for Bank 2 (driver side). They are located on the sides of the engine block, below the exhaust manifolds.
Can I ignore a knock sensor code like P0325?
You can drive the truck, but you shouldn't ignore the code. When the computer detects a bad sensor, it often defaults to a "safe" mode, which retards ignition timing. This results in reduced power and poor fuel economy. More importantly, it means the engine is no longer protected from damaging detonation if a bad batch of fuel or another issue arises.
What is "false knock"?
False knock is when the sensor picks up vibrations from another source and mistakes it for engine detonation. This can be caused by a loose exhaust heat shield, a rattling bracket, or even internal engine noise that isn't harmful. The computer will still pull timing, hurting performance, even though there is no real detonation happening.
Is replacing a knock sensor a difficult job?
For the Hemi-powered Ram 2500, it is a fairly straightforward job for a DIYer with basic tools. The sensors are not under the intake manifold like on some other V8 engines. The main challenge is reaching them, which usually requires working from underneath the truck. Access can be tight, but it does not require major disassembly.
🎬 Watch a professional technician replace a P0330 sensor on a HemiHelpful Videos
Technical Specifications
OEM Part Numbers: 68570138AA 5033316AB 5033316AA
For 5.7L & 6.4L Hemi V8 Engines. Two sensors are used, one per engine bank.
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.
- Ram 2500: