Error Code P0730: Incorrect Gear

You’re driving down the highway and something’s just not right.  You think it may be a transmission problem, but that covers a whole lot of territory because so many things that can go wrong with an automatic transmission.  Several of them will show up as a P0730 Error Code when hooked up to On Board Diagnostics (OBD), particularly a gear problem.

Understanding the P0730 Code

When an OBD registers a P0730, it’s just a starting point.  The code indicates that there’s a problem with what’s called a gear ratio, which is the relationship between the number of input RPMs to the resulting output RPMs. In an automatic transmission, one set of gears moves another; when the number of times the input gear is spinning isn’t in proper proportion to the spins of the output gears, the gear ratio is off.   In practical terms, the effort extended by your transmission isn’t producing the outcome it’s supposed to, which is more than just an inconvenience—it’s a sign of serious mechanical malfunction.

Symptoms of a Gear Ratio Problem

If there’s trouble with your gear ratio, you’ll notice it.  Among the signs: 

• Your check engine light comes on (admittedly, this could be a lot of things)
• You’ll notice slipping gears, jerking motions, and abrupt changes in speed
• Your gears may stick, possibly at a precarious time, such as while driving on a busy freeway
• Your car may stall after having been driven at high speeds
• You’ll notice an inordinately high number of RPMs for the speed you’re traveling
• Your fuel economy will be decreased, as your vehicle is working much harder than it needs to

Sounds like a pretty serious problem, right?  It is!  Yet depending on what’s causing it, the solution could be fairly simple—but you need to get to a mechanic ASAP to find out.

Getting to the Cause

Like so many other automotive issues, there usually isn’t one single cause of a problem.  When the P0730 code pops up, the investigation is just beginning.  There are many possibilities.

The best-case scenario is that your transmission fluid is low or dirty, in which case a flush and refill may be all that you need.  Similarly, you may have a clogged filter, also an easy fix.  (This is also a good wake-up call for remembering the importance of keeping everything under the hood clean and regularly serviced.

Another type of problem could be electrical.  Your transmission components operate on the commands they receive from your TCM (Transmission Control Module) or PCM (Powertrain Control Module). When the communication between those control centers and your transmission’s working parts is distorted by electrical failure or bad wiring, your gears aren’t getting correct instructions.  Fixing this kind of issue is a bit more involved than a simple fluid change, but it’s still relatively minor in the overall scheme of things.

A more serious situation is when the signs point to a component failure.  This could be several things: 

• A problem with your fluid line—there could be a blockage that’s simply not letting things flow, which means you will need a line replacement.
• A defective valve that isn’t regulating the proper flow of fluid
• Problems with the solenoid—the device that regulates the flow of fluid—or the torque converter, which translates engine power into speed
• A malfunctioning sensor that’s sending all the wrong messages to your PCM or TCM
• A faulty TCM itself, which is probably causing other problems, too.

There’s a Solution to Every Problem

Depending on what the mechanic finds to be the issue, the answers are pretty straightforward:  (1) Changes to fluid and/or filter are needed;  (2) Repair or replacement of electrical components is called for; or (3) Buying new components such as a solenoid is the solution.  The relative costs for each of these solutions vary, but if you put it off, the expensive could be much higher, such as a burned-out transmission that will have to be replaced, or worse yet, an accident caused by your inability to control your vehicle on the road.  So--Get it checked now and get it fixed!

Get Only The Best

Whether for prevention or repair, using the highest quality products for your vehicle is the key to keeping it “healthy.” Your best bet for those parts and accessories is Sun Transmissions.

 As a carrier of only top-of-the-line products, Sun Transmissions is your go-to source for your transmission and power steering needs.  We stock everything imaginable, from ATF additives, filters, switches, and gaskets to major components like solenoids and sensors, as well as overhaul and re-build kits.   And—for those of you in warmer climates like us here in Miami—even transmission coolers.  We’ll be happy to ship to you wherever you are, and, for orders over $80, shipping’s on the house!

Reach out to us today and let us know how we can help you get the most out of your transmission.