This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.
Transmission Component Slipping
When your vehicle codes P0894, it means some component of the transmission is slipping when it should be engaging with the rest of the powertrain. The powertrain control module (PCM) manipulates the gear ratios in an automatic transmission, and it simultaneously controls speed, fuel economy, acceleration and engine performance. When a gear ratio is not in sync with the control signal sent by the PCM, the module saves a P0894 code.
There is only a short list of reasons you’ll see this error code saved:
- Internal mechanical failure within the transmission itself
- Low, empty or contaminated transmission fluid
- Clogged or blocked internal transmission fluid passages
- Broken or damaged shift solenoids
- Damaged or defective transmission control module (TCM)
- Damaged or defective PCM
The first warning sign you’ll see is an illuminated Check Engine Light on your dashboard. You may experience other issues as the malfunction progresses like an inability to switch gears, transmission overheating, slippage when changing gears (starts to shift but fails to catch), and rough shifting (shifts and catches roughly). You may also notice a serious decline in your vehicle’s fuel economy.
I don’t recommend diagnosing this error code as a DIY project. The process is complex and potentially requires accessing, repairing or replacing internal transmission components. For most vehicles, troubleshooting a P0894 demands specialized lift and safety equipment and a high end diagnostic scanner. Unless you have access to those resources and are an experienced mechanic, let a professional do the following:
First, a technician will connect an OBD-II trouble code scanner and check the saved codes and the freeze-frame data. Not only does this give them a better idea of what may be causing the P0894, but it can also give them an idea of when the failure occurred and what the state of the engine and transmission were at the time of failure.
Next, the technician will reset all codes and restart your vehicle to test drive it. If the P0894 doesn’t pop up again, it’s possible that the code was saved in error or it’s an intermittent issue.
If the reset and test drive didn’t fix the problem, the technician will evaluate the condition of the transmission fluid. Low fluid means a quick refill followed by leak checks, and dirty or contaminated fluid means it’s time for a flush and refill.
Should the transmission fluid refill/exchange not do the trick, your technician will check out the internal parts of your transmission. If the gears and other mechanical components look to be in good shape, they move on to checking for issues like damaged wires, corroded/faulty connectors and frayed harnesses. They will replace any damaged wiring or connectors they find, as they are often the source of trouble codes in the absence of actual component failure.
Once they have ruled out fluid, wiring and mechanical problems, the technician will take a look at the shift solenoids and the control modules. If every other cause has been ruled out, chances are the problem lies with one of those two.
Your technician should be resetting codes and taking a reading each time they replace or repair something on your vehicle. This helps them verify if their most recent effort fixed the code or not, and it’s the mark of a highly trained and efficient automotive repair technician.
Most technicians go wrong with their diagnosis when they don’t follow the troubleshooting steps precisely. They end up replacing more expensive components like solenoids and modules when the actual root cause of the trouble code is a loose connector or a frayed wire. You want your technician to start with all the simple fixes first, and then have them move on to more complex explanations once they’ve ruled out the easiest first.
How serious is this?
Vehicles that save this code are generally drivable. Your chief concern should be the issue causing the code, as it may be causing permanent damage to your transmission. Ignoring this issue and hoping it goes away is why repair shops end up rebuilding or replacing entire transmissions. Better a correct and inexpensive fix now than an expensive repair later.
What repairs can fix the code?
Here is what most shops do to resolve a P0894:
- Refilling the transmission fluid
- A complete transmission fluid exchange
- Repairing/Replacing any wires, connectors and harnesses in the internal transmission
- Replacing the shift solenoids
- Replacing the TCM or PCM (only in rare circumstances)
Discovering that you have a slipping transmission component should cause you some alarm, but there is good news, too: if you haven’t noticed anything wrong with how your vehicle drives, you have probably caught the problem early. Waiting until you have shifting and drivability issues to get your transmission checked out is how you wind up with expensive repair bills. If you connect your OBDII scanner and see a P0894, book an appointment with your local repair shop and get it checked out. Hopefully it’s nothing serious, but the sooner you diagnose the cause, the better off you will be in the long run.