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Bully Dog Performance Chip for the 2013 Subaru Legacy

Bully Dog Performance Chip

Code:   BY40402



Shipping Special

Shipping Weight: 1.59 pounds


Bully Dog WatchDog Monitor - Color Screen - Black - 2013 Subaru Legacy

Keep a close watch on your Subaru Legacy's vital engine data with this easy-to-read display. Run diagnostics, set safety warnings, measure performance and view up to 4 parameters at once. Driving Coach program helps you to maximize fuel economy.


  • Provides a general-purpose gauge unit for towing and everyday use
    • 2.4", Full-color LCD screen with adjustable backlight is flanked by touch-sensitive buttons
    • US standard or metric measurements can be chosen
  • Displays up to 4 of more than 15 available parameters
    • Keep an eye on the function and performance of your engine
  • Maximizes fuel economy with the help of Driving Coach program
    • Understand how your driving style and/or various add-ons affect your Subaru Legacy's performance and efficiency
  • Supports aftermarket pyrometer kit (sold separately) to monitor EGT in diesel applications
  • Alerts you to changes and problems in engine function and performance
    • Set audible and visual alerts for engine protection
      • Monitor engine coolant temperature, transmission temperature, boost and EGT
    • Run diagnostic checks and clear trouble codes
  • Records, displays and saves 1/4-mile performance testing times
    • Download free programs to compare runs and to further analyze data
  • Installs quickly and easily
    • Connects to Subaru Legacy's computer via the OBD-II port for real-time monitoring of vital engine data
    • Guides you through initial setup process with Setup Wizard
  • Can be easily transferred between different cars or trucks
  • Complements your Subaru Legacy's interior with black finish
  • Includes universal suction-cup mount
    • Custom mounts (sold separately) available for certain applications for that from-the-factory look
  • 1-Year warranty

The WatchDog can request a variety of data from your engine's computer. Only those parameters that the computer replies to, though, can be displayed. So the type of information will vary depending on the make, model and year of your application.

WatchDog Driving Coach Display

Bully Dog WatchDog Driving Coach Program
  1. This area displays the Driving Coach on your screen. Monitoring this information will give you a good indication of how your driving habits affect your fuel economy and overall engine performance.
  2. In the top portion of the Driving Coach display is the Wasted Energy graph. This shows your deceleration and acceleration in relation to a base centerline. The centerline represents zero wasted energy. If you accelerate or decelerate too quickly, a color bar will extend out from the centerline, showing the energy expended.
  3. Below the Wasted Energy bar is the Driving Efficiency graph. This bar indicates how consistently you are driving. If you bounce back and forth between accelerating and decelerating too often or if you hit the gas and/or brake with a heavy foot, your driving efficiency will be "low."
  4. In the center of the Driving Coach display, you will see three measurements. This is the Average Mileage line. The first measurement is Average MPG. This number is calculated based on all driving activity from setup on, and it represents your overall, average fuel economy.
  5. Gallons shows the estimated total number of gallons of fuel used.
  6. A Grade is given for your overall driving performance, and it is based on the information provided by all Driving Coach indicators. It ranges from "A" for optimal performance to "Epic Fail," indicating the need for a tune-up, as well as a change in driving habits.
  7. The bottom row on the Driving Coach display is the Instant Economy and Trip line, which shows three measurements. The first is Instant MPG. This represents your fuel economy at a specific moment in time and can be used as an instant indicator of driving performance.
  8. Trip MPG refers to the average fuel economy for a certain trip. This cumulative average resets every time that the WatchDog is turned off.
  9. Trip Grade is the grade that you are given to mark your performance for a single trip. This, too, resets each time the monitor is turned off.

When you are parked or idling for a certain period of time, driving tips will pop up on your screen. These are chosen based on your individual driving efficiency and are designed to help you improve fuel economy.

Monitoring Your Engine

Choose from more than fifteen parameters to monitor. Note: Not all of the following are available for all applications.

  • Engine load - no load = 0 percent; maximum load capacity = 100 percent
  • Coolant temperature
  • Fuel rail pressure (for diesel engines only)
  • Turbo boost pressure (pressure generated by the turbocharger) - monitored for safety
  • Engine RPM
  • Speed (mph or kph)
  • Ignition timing (gas engines) or injection timing (diesel engines)
  • Intake temperature - at point where OEM sensor is installed within air intake stream
  • Mass airflow (grams/second) - amount of air entering air intake stream
  • Throttle position - idle position = 0 percent; full throttle = 100 percent
  • Fuel level
  • Battery voltage
  • Barometric pressure
  • Real-time fuel economy
  • Average fuel economy
  • Trip fuel economy

You can monitor up to four parameters at a time, with each displayed along the left side of your screen. To view detailed information about any one of those factors, touch the button next to it, and the large gauge area on the right will display the information for that parameter. You can further customize the gauge to display in one of the following styles: analog, analog with mini-graph, or full graph.

40402 BullyDog Watch Dog Multi-Function Performance Gauge - Black


Ask the Experts about this Bully Dog Performance Chip
Do you have a question about this Performance Chip?

  • Ability of Bully Dog Watch Dog Gauge Monitor to Correct Speedometer for Larger Tires
  • Because the Bully Dog Watch Dog is a monitor only, it is not capable of programming or changing anything on the vehicle, including the speedometer calibration. However, the Watch Dog does have a speedometer display function that can be calibrated for accuracy, see page # 23 of the owners manual, which I have linked you to. While driving, you would just ignore the speedometer reading on the vehicle and go by the corrected speedometer reading shown on the Watch Dog.
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  • Performance Chip to Increase Horsepower and Improve Gas Mileage on a 2003 Ford F-150 5.4L
  • We carry a few programmers that will increase the horsepower and help improve the gas mileage of your 2003 Ford F-150 5.4L. The Edge CTS Programmer, # EP85250, and the Edge CS Programmer, # EP85150, will give your truck up to 15 additional horsepower and 20 foot pounds of torque. The economy power level will create less overall power for everyday driving to improve your trucks fuel efficiency. In addition to the economy power level, both programmers include the Mileage Coach program...
    view full answer...

  • Do the Available Programmers Increase Horse Power and Fuel Economy for a 2012 Toyota Tacoma
  • All of the units for a 2012 Toyota Tacoma, see link, are monitors, not tuners, and will allow you to view various performance parameters of the vehicle but will not allow you to tune the engine. This means that you will not get any horsepower or torque gains but by monitoring fuel consumption you can increase fuel economy by changing driving habits based on the data presented by a monitor. The BullyDog unit specifically has a Driving Coach program which will help maximize fuel economy...
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  • Availability of Performance Chip for 1988 Ford Ranger XLT
  • Although we offer performance monitors for the 1998 Ranger that can monitor different performance parameters at a given time, an actual performance chip that would alter the engine computer to influence performance is not available. The Bully Dog # BY40402 (black monitor) or # BY40400 (white monitor) can display up to 4 of 15 available parameters at a time, and can monitor parameters like engine load, coolant temperature, RPM, throttle position and average fuel economy among others....
    view full answer...

  • Performance Tuner for 2014 Dodge Charger with 3.6 Liter Engine
  • The Bully Dog WatchDog you referred to part # BY40402 is a monitor, it will allow you to observe up to 4 of 15 different performance parameters at the same time. It is not capable of changing the tune of the engine. None of our vendors offers a turner for the 2014 Charger with the 3.6L engine. The WatchDog will allow you to monitor such parameters as Speed, Boost (turbo equipped vehicles only), RPM, Coolant Temp, Throttle Position, Barometric Pressure, Battery Voltage, Fuel Pressure,...
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  • Can the Bully Dog Watch Dog Monitor Display Transmission Temperature on a 2009 Ford Escape
  • The monitors that we carry have specific functions for specific vehicles. The parameters that a particular unit can display depend on what information is fed through the OBD II port on the vehicle. My contact at Bully Dog was unsure of whether or not the computer on the Escape will answer the request from the Watch Dog for the transmission fluid temperature. Since the Edge CTS could not display it that is a good indication that the vehicle computer does not allow or cannot display this...
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  • Will Bully Dog Triple Dog GT Platinum Gauge Tuner # BY40417T Work on 2007 Toyota Tundra 4.7L V8
  • The particular Bully Dog Triple Dog GT Platinum Gauge Tuner # BY40417T that you referenced is not a fit for your Tundra with 4.7L V8 engine. This tuner is compatible only with the 5.7L displacement V8 Tundra. For your truck we currently do not offer any performance tuners, only monitoring devices such as the Bully Dog # BY40402. This unit installs in the same manner as a tuner,via the OBD-II port, but its function is limited to displaying engine information. It does not alter any engine...
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  • Programmer and Monitor Recommendation for a 2012 Chevy Silverado with a 6.0 liter Gas Engine
  • Yes, the Bully Dog WatchDog Monitor # BY40402 that you referenced will work on your 2012 Chevy Silverado with a 6.0 liter gas enginge. However, you should note that this is ONLY a monitor. It will not provide you with any additional performance, only the ability to monitor engine and transmission parameters. If you wanted a programmer that would give you additional performance you would want the part # BY40410GMC.
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  • Availability of a Performance Chip for 2003 Jeep Liberty
  • We do offer performance monitors for the 2003 Jeep Liberty that can monitor different performance parameters at a given time. The Bully Dog # BY40402 (black monitor) or # BY40400 (white monitor) can display up to 4 of 15 available parameters at a time, and can monitor parameters like engine load, coolant temperature, RPM, throttle position and average fuel economy and more. The Bully Dog monitor can also scan and clear trouble codes and includes the driving coach display that can monitor...
    view full answer...

  • Performance Monitor Recommendation For 2001 Hyundai Elantra
  • The performance chips available for your 2001 Hyundai Elantra are monitors, which do not tune the engine or change the settings. I recommend the Edge Performance Chip, part # EP83830, for your Elantra. This system allows you to view up to 8 parameters at one time on the 4-1/3 inch high-res touch screen. This system also reads and clears trouble codes and includes a mileage coach which can help you maximize your fuel economy. This unit is easy to install, by simply plugging into the...
    view full answer...

  • Does the Bully Dog WatchDog Tune the Engine on a 2006 Hummer H3
  • The Bully Dog WatchDog, # BY40402, is a monitor or comprehensive gauge display only. It is not a programmer that will allow you to change the tune of the engine. It allows you to view various parameters of the vehicle performance. At this time there are no programmers we carry that allow you to change the tune on your 2006 Hummer H3. Your best option is actually to visit a local performance shop and get a custom tune for your Hummer.
    view full answer...

  • Available Programmers for a 1999 Dodge Ram
  • There are options for programmers available for your 1999 Dodge Ram, but the Bully Dog WatchDog Monitor # BY40402 you referenced is only a monitor that allows you to view gauges and information from the OBD-II port of your vehicle. For the available programmers and monitors available for your vehicle check out the link I attached. You will need to select your engine from the drop down menu. The horsepower rating of the programmer will be listed on the page as well.
    view full answer...

  • Availability of a Performance Tuner for a 2014 Ford Expedition
  • Edge and Bully Dog offer Gauge Displays like the touch screen # EP83830, the color screen # EP83730 or the WatchDog monitor in black as # BY40402 or white as # BY40400. A gauge display cannot change the factory tune of the engine, but they will allow you to observe several different performance parameters of the drivetrain in real-time. Edge provides the Mileage Coach and Bully Dog has the Watch Dog system, that can observe your driving habits and report back to you, telling you how your...
    view full answer...

  • Will Bully Dog WatchDog Monitor # BY40402 Increase the Horsepower for 2014 Dodge Dart
  • The Bully Dog WatchDog Monitor, # BY40402, that you referenced allows you to keep a close watch on your vehicle's vital engine data, run diagnostics, set safety warnings, measure performance and view up to 4 parameters at once. The WatchDog, # BY40402, is strictly a monitor and will not alter the performance of your 2014 Dodge Dart. At this time there are no performance tuners available for the Dart. If you are looking to increase your horsepower, you may want to visit a local performance...
    view full answer...

  • Modification Recommendations for a 2005 Mercury Grand Marquis
  • Yes, a cold air intake like part # AFE54-11692 that is confirmed to fit your vehicle will give you additional fuel mileage. The Bully Dog WatchDog Monitor # BY40402 is not a programmer so it will not directly give you better fuel mileage, but it does have a driving coach that can help you improve your driving habits to maximize fuel mileage. This is not a chip or a programmer though and will not provide you with a different tune for your vehicle to run on. We do not offer any confirmed...
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  • Difficulty of Restoring Stock OEM Tune in 2014 Dodge Ram Having Warranty Service
  • Re-installing the stock tune to a vehicle that has been re-programmed with an alternate tune is a simple process. You will simply connect the tuner to the OBD-II port as you did when you installed the alternate tune and select the "stock" setting from the menu. The vehicle's original tune is stored inside the memory in the tuner so that you can retrieve it when you want to take the truck in for warranty service at the dealership. The link provided will show you all monitoring devices...
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  • Parts Included in the Bully Dog Performance Chip for 2005 Lincoln Aviator
  • The Bully Dog Performance Chip for the 2005 Aviator, part # BY40402, has everything you will need, including the Watchdog Head Unit, OBDII Adapter Plug, Power Wire, Main Wire Harness, Mini USB Cable, Micro SD Card and Windshield Mount. I have included the installation instructions which includes a list of included parts and parts description for you to check out.
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  • Bully Dog WatchDog Monitor Recommendation for a 2003 Toyota 4Runner
  • If you are looking for a Bully Dog monitor that is confirmed to fit your 2003 Toyota 4Runner you would want the part # BY40402. I checked with Bully Dog and this monitor has been confirmed as a fit for you. There are no performance tuners like the part # BY40450 that you referenced confirmed to fit your vehicle.
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  • Availability of Performance Tuner Chip for 2014 Lincoln Navigator with 5.4L V8 Engine
  • For your 2014 Lincoln Navigator with 5.4L V8 engine we do offer several choices of monitoring displays from Edge and Bully Dog, but none of these is actually a tuner. Currently no performance chip is offered or your 2014 Lincoln Navigator. Although older vehicles with the same engine may have confirmed performance tuner applications available it is possible that updates to the computer/electronics in your 2014 make it incompatible. The monitors offered for your Navigator can be...
    view full answer...

Subaru Legacy Accessories

Info for this part was:

Photos by:
Jackie C

Expert Research:
Michael L

Written by:
Lindsey S

Expert Research:
Michael H

Expert Research:
Jameson C

Expert Research:
John H

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