Fault code P0802 is called “Transmission Control System MIL Request Circuit Open” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0802
This diagnostic trouble code (DTC) is a generic transmission code. Error P0802 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
Many vehicles have an automatic transmission control module called a transmission control module (TCM). The engine control module (PCM) communicates with the TCM. To monitor the automatic transmission for malfunctions.
If your vehicle retains code P0802, it means that the transmission control module (PCM) has received a data input signal. This indicates that the transmission control system (TCS) has detected a problem that requires the malfunction indicator lamp (MIL) to turn on.
The Malfunction Indicator Lamp (MIL) should illuminate to let the driver know there is a problem. But the MIL does not illuminate because an open circuit has been detected.
P0802 is an information code only. Which does not indicate a direct engine problem, but only a general malfunction in the transmission. Additional diagnostics are needed to determine the exact picture. This requires a diagnostic scanner to communicate with the transmission module.
Symptoms of vehicle malfunctions
The main signal that an error P0802 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- You may have difficulty shifting gears while driving.
- Unstable or abrupt gear shifting.
- Shifting gears takes a long time.
- The transmission may be put into emergency mode.
A stored code P0802 indicates that a potentially serious TCS fault has been detected. The conditions that contributed to the stored code should be corrected as soon as possible.
Factors that can cause this error code
The error code P0802 can mean that one or more of the following problems have occurred:
- Short circuit in TCM (transmission control module).
- TCM (Transmission Control Module) may be defective.
- Short circuit or wire breakage.
How to fix or reset OBD-2 code P0802
Some suggested steps for troubleshooting and fix the error code P0802:
- Check wires for breakage, melting.
- Check all PCM / TCM connectors one by one.
- Test the PCM / TCM modules.
After all the above steps, remove the error code DTC P0802 with the scan tool. After that, it is worth to test-drive and check if the error will come back.
Diagnose and repair of problems
The first thing to do when diagnosing a P0802 fault is to check the electrical part for damage. In today’s vehicles, electrical and electronic signals require good cabling for proper data transmission. Any faults, such as breaks, disconnected connectors, or corrosion, can interrupt signals, resulting in transmission control failures.
Check the battery pack, as some PCM and TCM modules are sensitive to low voltage. If the battery is low, the system may detect this as a failure. Make sure the battery is putting out at least 12 volts, and that the alternator is running properly, at least 13 volts at idle.
Low ATF fluid levels can result in no pressure in the box, which can also be a problem that the TCM detects as a failure. Fuses should not be overlooked either, as a blown fuse is a common problem.
On which vehicles does this problem occur most frequently
Fault code P0802 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Chevrolet (Silverado)
- Dodge (RAM)
- Ford (Sierra)
- GMC
- Kia
- Mercedes-Benz (CLS550)
- Peugeot (307)
Fault code P0802 can sometimes be found with other errors. The most common are the following: P0089, P0380, P0404, P0898, P0899, P1093, U2106.
