What it means
The transmission control system MIL request circuit is open or has a fault. The code does not establish whether the request is sent over a dedicated wire or by network communication.
At a glance
- Usually lights the check-engine light
How it works
The transmission control system can request that the malfunction indicator lamp (MIL) turn on, either through a dedicated circuit or through network communication. P0802 sets when the request circuit or its communication path is open or faulty; the code alone does not specify which path the vehicle uses.
Common causes
Most likely first.
- Open MIL request wire
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Scan the engine and transmission modules for related codes and save freeze-frame data before clearing anything.
- Check module data for an MIL request and compare it with whether the dashboard lamp illuminates.
- Use the vehicle wiring diagram to identify whether the request uses a wire or network communication, then inspect the relevant connectors and harness.
- For a dedicated wire, test continuity and shorts; for a network path, check for related communication codes and inspect network connections.
- If the external circuit checks out, inspect module connector pin fit and investigate an internal module or solder-joint fault.
Common fixes
- Reseat a loose connector or pushed-back pin in the MIL request circuit.
- Repair an open, shorted, or damaged request wire.
- Repair a confirmed network connection fault.
- Repair or replace a module only after its circuit or internal fault is confirmed.
Can I keep driving?
If shifting is normal, a short trip may be possible, but arrange diagnosis soon because the transmission warning request may not be reported correctly. Avoid driving if the transmission slips, shifts harshly, or enters a limited gear mode.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.