Q: Mustang engine swap. The speedometer doesn't work now. Why? Mustang

asked by on November 21, 2016

Have a mustang that my son put an engine from another car in it. The speedometer doesn't work now. What if the engine speed sensor is not the same? Will this cause the speedometer to bu out of calibration with the speed sensor? How do I remedy this problem?

Speedometer is not working Inspection $94.99 - $114.99 Get a Quote

Hello - the speedometer is driven by a sensor on the transmission. Perhaps this problem is because the sensor was not re-connected after the swap? If the transmission was also swapped, it is possible the sensor on the donor transmission is not compatible with the wiring and speedometer gauge on the vehicle. I would recommend an inspection of the speedometer components by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How do I display the miles to empty feature?
There is a Base Message Center that logs the functions of your vehicle. You can use this message center to display your vehicle's information and features. The Miles to Empty feature will tell you how long it will be before...
What types of lockout protection are offered?
Locking up your car is vital for security, but what if you lock your keys in the car? We’ve all done it (or come very close). Thankfully, your car offers some important forms of lockout protection to help ensure you...
How do the front air bags work?
Your Honda Accord is equipped with front air bags that are designed to deploy during certain impacts (moderate and severe impacts, but not in minor accidents). Sensors detect the impact and calculate the severity. A signal is sent to the...
Car not riding smoothly
Hello. It appears that you have a series of issues occurring. If the vehicle itself is not riding smoothly then it may have an issue with the struts. Due to the age of the vehicle the struts may no longer...
Gear shift not going into gear
It sounds like your shifter assembly may be broken. I would recommend having the shifter replaced by a professional. This would require removing the steering column and a few other trim piece in order to access the bolts that mount...
Is it possible to install my broken serpentine belt back my car?
Hi, thanks for writing in. I'm a little confused by your question. If you're asking whether it's possible to install a broken serpentine belt (https://www.yourmechanic.com/article/how-to-replace-a-serpentine-belt-by-mia-bevacqua) on a vehicle and drive 20 miles, I'd say not. If the belt is physically...
Transmission. Car turning off when changing gears.
Hi there, thanks for writing in. This is a common issue on a lot of Nissan vehicles. Most of the time it is due to a faulty throttle body. The throttle motor fails at times and cannot keep the throttle...
TIᖇE ᗷᖇOKE Oᖴᖴ ᖴᖇOᗰ ᐯEᕼIᑕᒪE
Hi there: We really would need to know what type of vehicle you have to accurately tell you what components might need to be repaired or replaced. In most cases, when a tire falls off, it's due to faulty wheel...
Transmission won't go in reverse.
Hi there. Sounds like the transmission shift position sensor is not working properly. I recommend replacing the sensor. The transmission position sensor is designed to tell the computer (ECM) what gear the vehicle is in. If the dash is saying...

Related articles

How Long Does a Ride Control Module Last?
Once Once upon a time, automotive suspensions were pretty primitive. They’ve evolved a lot since then, and there are several types in use today. Most cars use springs and shocks/struts, but some vehicles use an air suspension system. This type...
P0713 OBD-II Trouble Code: Transmission Fluid Temperature Sensor Circuit High Input
P0713 means the automatic transmission fluid is too hot due to low or dirty transmission fluid, slipping or damaged transmission or damaged wiring.
The Worst Cities to Break Down In
Here's where you'll find the highest car repair costs, worst public transportation, and congestion.