Skip the auto shop - Our mechanics make house calls

Q: Car is running slow, what could it be?

asked by on

The codes I’ve been given are P0502 & P1406. My check engine light is on & my speedometer isn’t working; it’ll get up to what feels like 30 mph & sometimes do a jerking motion/speed up or start to slow down. I've also noticed that on the right side a fan will start up & my car makes struggling noises. I’ve been told to check my Transmission Fluid, but that looks like the proper color & fills to both holes on the dip stick. I’ve had a mechanic come out once for checking the problem & again to fix a possible solution (speed sensor). After the 2nd time, he told me I would need a speed sensor pigtail connector, which I found & need replaced. Any suggestions if that might not work?
My car has an automatic transmission.

A: If you already replaced the sensor then now...

If you already replaced the sensor then now it will need that connector you’ve mentioned. Replacing it may fix the code P0502. The code P1406 is for the EGR valve position, you would need to have the valve tested to see if it is stuck open or if the valve is bad. Have a pinpoint test done on the code P1406. I suggest to have a qualified technician perform these checks and properly diagnose your trouble codes further. From there they can perform the necessary repairs. Good luck

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
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

Get a quote

What others are asking

Q: Weird green fluid coming out of overflow tank. Right after that, the car almost overheated

Hi, thanks for writing in. Unfortunately, it appears as if you may be correct about the head gasket issue - especially when you indicated you noticed that the dark green, "MILKY" fluid. The milky is caused by oil mixed with...

Q: The car starts, but when I hit the gas the check engine light blinks & it feels like I don't get much power, sometimes smell gas.

Hello. A flashing Check Engine Light is an indicator that the computer has detected an issue with the vehicle's engine management system that could potentially cause harm to the emissions system. Continuing to drive with a flashing Check Engine...

Q: P0113

The code is for a malfunctioning Intake air Temperature sensor. A failure here may cause a hard or no start as the part usually fails in a way where the signal defaults to a cold temperature and the computer tries...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.