Skip the auto shop - Our mechanics make house calls

Q: What Do Transmission Error Codes Tell You?

asked by on

What do transmission error codes tell you?

A: Using transmission error codes is a necessa...

Using transmission error codes is a necessary procedure for a transmission technician since automatic transmissions have been computer controlled for over 20 years. The transmissions currently in use are very different to diagnose and repair than transmissions from decades ago. For correct operation, transmissions rely on accurate electrical inputs from multiple sensors. A transmission control module (TCM) processes the inputs, “decides” what the correct action is for the current conditions, and sends out commands to actuators. The required training, electrical understanding, tooling, and diagnostic skills required of transmission technicians have all increased dramatically. Fortunately, the automatic transmission control systems are designed to be able to provide some clues to a technician about what “might” be faulty. These are the fault codes or error codes. A technician obtains them from the vehicle’s control module using a scan tool. Codes may indicate issues with the speed sensors, shift solenoids, pump pressures, valve body circuits, or slipping clutches. The fault can be the TCM itself, programming calibration, or electrical wiring, connections, or grounds for any of these. The scan tool and code doesn’t tell a technician what part to replace, but does provide direction to an experienced, trained technician in the diagnostic process.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: As I was getting on the interstate, my RPM's jumped to 5 and my car started jerking but never died. I built speed back up to about

You should check the transmission fluid level and smell the fluid to see if it smells burnt. The problem sounds like you have a transmission that is slipping and should have a mechanic like one from YourMechanic check the vehicle...

Q: My vehicle display says my car isn't in park when I go to start it ,HELP!!

It sounds like you may have a faulty shift cable for the transmission. It may have a bad connection bushing where it connects to the transmission linkage. You should have the cable inspected to see if it is bad and...

Q: my car make rattling noise ,feel like it stops and goes,while driving, and now displays "check engine"

Inasmuch as the check engine light has illuminated, diagnostic trouble codes have been stored in your car's engine computer (PCM) and those codes, once downloaded, will probably reveal at least the general cause of the problem you are having. If...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...