While many other cars will throw a message on the dash to let you know what exactly is happening with the vehicle. Vauxhall still likes throwing codes. I’ve already told you about the Code 16 problem, and now it’s time to talk about the more serious issue – Code 84.
Simply put, Code 84 means that the engine power is reduced by the ECU and you can only drive at a certain low speed like 5 MPH. So, this code just means that the ECU has just put your Vauxhall into the so-called limp mode or “take-me-home” mode.
In this article, I will try to tell you everything I know about the Code 84 problem and ways to fix it.
What happens when you see Code 84?
In this case, you will most likely experience low engine power. The usual thing for Vauxhall cars is to set the maximum speed to 5 MPH. At this speed, you can safely limp your car to the garage or to the dealership and let professionals inspect the issue.
Usually, you can’t accelerate when you see this code and will have to move to the side of the road, turn on both blinkers (emergency lights), and move slowly to the place where you can safely park.
What are the reasons for Code 84?
Any modern Vauxhall vehicle can show this problem. Unfortunately, Code 84 doesn’t show any certain problem that you can quickly check and fix. It only tells you that the limp mode has been activated and now you can’t drive at a high speed.
Also, when you see Code 84 on the dash, you should also know that there is another code in the ECU or other control units. Knowing this code will certainly help you but to get it out you will need a proper scanner.
Here are the most common reasons for Code 84 in Vauxhall cars:
1) Throttle position sensor issues
The throttle position sensor is the part that sends the data about the position of the throttle flap to the ECU. The readings are needed for idling RPM adjustment and also for controlling the revs of the engine when you drive.
This is especially bad in cars with electronic throttle. In case something happens with the sensor, your vehicle will limit the power significantly.
While sometimes it’s just a problem with sensor glitch or wiring, in most cases, the expensive sensor needs to be replaced.
2) Intake or fuel supply problems
Air intake sends air from the atmosphere (or from the turbocharger) into the combustion chamber. If there is a blockage, a dirty filter, a bad pipe, or a malfunctioning mass airflow sensor, the engine will freak out. Of course, the ECU will set it to limp immediately.
Fuel pump problems or clogged fuel filters may also reduce the pressure of fuel in the system and lead to the same problem. Also, malfunctioning or dirty fuel injectors may affect your engine work significantly.
All of these problems may lead to Code 84. And you may also see some error messages like Engine Fault, Repair Needed.
3) Misfiring engine
Modern engine control systems count misfire events. If a certain cylinder misfires once or twice, it’s OK and the ECU won’t even save the code for this. But if misfiring becomes abnormal, the limp mode can be activated to avoid engine damage.
Usually, you will feel engine power limitation even before the Code 84 problem appears. The engine can misfire because of spark plugs, ignition coils, fuel pressure, air supply issues, compression problems, etc.
4) Software glitches
Unfortunately, it’s very common for modern Vauxhall cars to torture their owners with hundreds of possible glitches in the onboard software. Every electronic control unit (and there are dozens of them) has certain software to control the functions it is responsible for.
Once something happens with the module itself, wiring, or software, it’s not uncommon for the entire control system to stop working correctly. It’s very hard to locate the problem because it can mysteriously appear and disappear.
5) Engine overheating
It’s quite often that the Code 84 warning pops up when your engine is overheated. In this case, the ECU will limit the revving of the engine and you will only have the limited power available to drive further.
Of course, the reason for overheating should be found. I strongly recommend against driving with an overheated engine, even limping can hurt it, so turn the engine off and let it cool down first. Then, let a professional inspect the engine and find the reasons why it could overheat.
6) Other minor problems
There are dozens of other small issues that could cause this warning to pop up. I can’t list them all – it would take a lot of time and effort. I’m sure that the majority of cases with the Code 84 warning will fall under the previously mentioned issues, but there is still a small chance that you have another problem that needs to be properly diagnosed.
What can you try doing to get rid of Code 84?
If you are in the middle of nowhere and suddenly see Code 84 on the dash of your Vauxhall, it’s hard to imagine how long you will be driving to the nearest dealership. So, here are some things you may try to get rid of the limp mode limitations:
- turn the vehicle off and then on
Since all modern cars are gadgets, this may help you get rid of the message. Especially, if this is a software glitch that could be fixed by just cutting off the power to a certain control module.
- let the engine cool down
If the temperature gauge shows a higher temp than usual, let your engine cool down for 15-20 minutes. Then start the car and check if it still shows “Code 84”. Maybe, it will allow you to drive several miles till it throws the code again. Avoid overheating!
- disconnect the battery for some time
By disconnecting the battery, you cut off power from all electronic control modules. So, they reset and eventually, you can just clear the codes that cause the limp mode. Disconnect the negative terminal, then the positive one, wait for several minutes, reconnect the battery, and try starting the vehicle.
- inspect the engine
Among the things that you can check are the turbocharger pipes, air filter, air supply pipes, throttle flap blockage, etc. Try finding anything that looks weird and unusual. Maybe, some pipe has fallen off and needs reconnecting. Or the air supply is blocked due to a dirty filter.
What if nothing helps?
At least, your vehicle is not completely dead and you aren’t stranded. You can still drive. But make sure the engine temperature is OK and there are no visible leaks or other issues under the hood that can affect the engine even worse.
Head directly to the dealership or at least to some place where you can safely park your car. Also, you may choose any other garage near you (unless your Vauxhall is still under warranty).
Alternatively, you may want to call a tow truck if you are far away from any garage or dealership. This will save you hours of your time.
In modern vehicles, there is almost nothing you can diagnose and repair on your own. So, if the DIY fixes I recommended above don’t work, you will have to take your car to the dealer. A good scanner will show all the codes and an experienced mechanic will fix the vehicle. Usually, it’s nothing really serious or expensive.
What if I have the scanner?
Use your scanner and read the codes. It’s very helpful if you have the Vauxhall-compatible scanner that communicates with different control modules. The simple EML scanner will only read some codes from the ECU and won’t give you an overall understanding of what’s happening with the vehicle.
Whatever scanner you have, try using it and see what codes it shows. Then google the codes with the name of your car model and see if there is a simple solution to the problem. In most cases, you will be able to get rid of the limp mode, at least for some time.
Do you want to add something and share your experience with the Code 84 problem in Vauxhall? Please write in the comments below!
