P0802Generic code

P0802 Code: Transmission Control System MIL Request Circuit

The P0802 code means there is a fault in the circuit the transmission computer uses to ask for the warning light. The transmission works, but the driver may not get a warning. It is a minor code that is cheap to fix and safe to drive with.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$5 to $300
Difficulty
Easy
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0802 code means

The transmission computer asks the engine computer to turn on the warning light when it detects a problem. It does this either directly or by sending the command over the communication network. When that request circuit has a fault, the P0802 code is stored.

On modern vehicles the fault is usually in the communication with the instrument cluster or with the engine computer. On older ones it is a bulb or a wire.

Always start with the simplest items: fuse, relay and connector. Then check power, ground and signal with the component connected (using back-probes), and finally the continuity of each wire up to the computer. Only if all of that is good should you replace the component.

P0802 code symptoms

  • The warning light or indicator does not work.
  • Check engine light on.

Likely causes of the P0802 code

  1. Burned out bulb or LED on older vehicles.
  2. Wiring between the computer and the instrument cluster cut or shorted.
  3. Communication fault. Check for U codes.
  4. Instrument cluster with an internal fault.

How to diagnose the P0802 code step by step

  1. Watch the bulb check when you turn the key on.
  2. Check for communication codes.

How to fix the P0802 code

  • Repair the wiring, the bulb or the communication.

Technical reference data

  • When you turn the key on, the warning lights should come on for a few seconds.
  • These are approximate values: check the manufacturer data for your vehicle.

Brand-specific notes

On many vehicles you need a scan tool with access to the instrument cluster in order to diagnose this code.

Frequently asked questions about P0802

What does the P0802 code mean?
It is a generic OBD2 code that means the circuit the transmission computer uses to request the warning light has a fault. The transmission itself keeps working.
Can I drive with a P0802 code?
Yes. The transmission works normally, but remember you may not get a warning light if the transmission develops a problem.
Is it important?
The warning exists to tell you about transmission faults, so it is worth fixing, even though the code itself is minor.
What usually fails?
The wiring or the communication.
How much does it cost to fix P0802?
Between $5 and $300. A bulb is at the low end, and diagnosing a communication fault is at the high end.
Will a P0802 code clear itself?
If the cause was a brief communication glitch, it may. A burned out bulb or damaged wire will keep the P0802 code coming back.
What is the most common cause of P0802?
On modern vehicles, a communication problem with the instrument cluster or the engine computer. On older ones, a bulb or a wire.

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