What Happens Before a Gearbox Repair?
If you’ve ever taken your vehicle in to have its gearbox serviced and/or repaired, then you might have noticed the mechanic taking a few important steps before they set to work. With the gearbox — especially an automatic gearbox — being one of the most complex systems on your vehicle, it’s logical that even the most skilled mechanics and technicians would not be able to diagnose and fix the problem with it just by looking at it. They would need to get a firmer idea of what’s wrong before they could actually do anything about it.
Well, that’s where the work before the repairs comes in. Before a gearbox actually gets repaired, there is another main task to deal with, and that’s a vehicle diagnostics test. In today’s blog, we’re going to look at these tests, why and how they’re conducted, and why they’re so important when it comes to fixing your transmission and other components of your vehicle.
What is a Vehicle Diagnostic Test?
Your gearbox is a pretty complex piece of equipment, which is why a good mechanic always runs a diagnostic test before getting started. The test is a simple scan of your vehicle’s on-board computer system to try and determine exactly where problems are occurring. In other words, the test is a procedure that helps mechanics more quickly identify and diagnose what’s wrong with a vehicle.
How Is the Test Carried Out?
Diagnostics tests have become easier and faster than ever to carry out thanks to one special piece of equipment that is still used everywhere — the OBD-II (OBD: On-Board Diagnostics) scanning tool. Right under the driver’s cockpit in your car, if you go down there and take a quick look, is a very special port called the OBD-II port. The scanning tool plugs directly into this port and then at the push of a button scans your vehicle’s on-board computer system to see which errors have occurred.
The machine then quickly reports errors in the form of a special code known simply as a diagnostics code, or a fault code. Below are some of the most common fault codes that emerge:
- P0420 – catalyst system low efficiency
- P0300 – random/multiple cylinder misfire
- P0141 – oxygen sensor
- … and many more
The letter at the start of the code is not random. The “P” in the above common examples stands for “Powertrain” and other code starters include “B” (body), “C” (chassis), and “U” (network & vehicle integration). The numbers, too, are far from arbitrary. If the code starts with a “0” then it means it’s a generic/global code, if it starts with “1” it means it’s OEM-specific, and if it starts with “2” or “3” then it could be either generic or manufacturer-specific depending on the exact combination.
How Often Does a Car Need a Diagnostics Test? How Much Is It?
There’s no fixed timeframe that dictates exactly when diagnostic tests should be carried out on your vehicle. A good rule of thumb to follow is to always ensure the mechanic runs a full diagnostics test as part of your annual service. Alternatively, a diagnostic test should be run any time that you encounter a warning light such as a transmission warning light, “Check Engine” light, or something else.
The “Check Engine” light in particular is a good cue for a diagnostics test because there are so many possible reasons as to why the light has illuminated. Plugging in the OBD-II scanning tool will help narrow down the cause of the light coming on, and allow the mechanic to look straight at it. A fee of anywhere between £50-100 might be applied for running diagnostics, but it depends on your individual garage. It always works out cheaper than a mechanic’s traditional method of spending hours trying and checking everything until they encounter what the exact problem is.
It is actually possible to buy OBD-II diagnostics machines for oneself, with units being available online usually for under £100, but it depends how advanced it is. Some people buy them and run scans themselves before going to the garage so that they can report error codes in advance.
Why Are These Diagnostics Tests Important?
To wrap up, let’s look at why these tests are so important and how they benefit us all in the long term.
They Speed Up Repairs in General
Without the diagnostics test, the mechanic could only use reported observations from the customer — strange noise, leak, excess heat, etc. — and then their own observations to make educated guesses as to where problems are. They’d then have to follow these up with comprehensive checks that in the case of the transmission might mean essentially taking the whole thing apart to inspect each component.
The diagnostics tool allows for rapid checks that focus a mechanic’s attention in the right place in seconds, resulting in faster maintenance and repairs.
They Help Technicians Navigate the Transmission
As we’ve mentioned further above, the transmission is a tricky piece of equipment, and the diagnostics tool helps the mechanic to navigate the system to find where problems are. Using the codes generated by the scanner, the mechanic will know which part of your gearbox to target, rather than having to dismantle and check every component.
Diagnostics Allow Problems to Be Found Early
When you run diagnostics scans as a matter of course, you can reveal problems within your car’s mechanical workings that haven’t yet even manifested in a way that’s detectable to you. In finding the problems early, you can fix them before they become too serious and do major damage to your vehicle. Almost all the most serious things that can go wrong with your gearbox and other systems start as tiny errors that steadily grow into catastrophes.
Diagnostic Tests Will Save You Money
Following on from the previous point, running diagnostic tests and discovering problems early means that you enjoy cheaper repairs, which in the long run saves you a lot of money. Fixing a car problem cheaply now will always be better than waiting for it to become an expensive mess.
Diagnostic Tests Will Resolve Warning Lights
Finally, if and when your dashboard is lighting up like a Christmas tree with warning lights for this and that, running diagnostics tests will resolve the lights and put your dashboard back to normal. Most importantly, the scanning tool will determine whether or not the warning light has come on because there is something wrong with your car, or because there is a problem with a sensor that is causing the light to come on erroneously.