P0800
PowertrainTransmissionmoderate severityTransmission Control System (MIL Request)
What P0800 Means
The transmission control module has detected a fault and is requesting the malfunction indicator lamp be illuminated. This is a general communication code indicating the TCM wants to alert the driver to a transmission issue.
Symptoms
- Check engine light on
- Transmission warning light
- Possible shifting problems
Common Causes
- Faulty transmission control module
- Wiring or connector fault between TCM and PCM
- Stored transmission fault triggering MIL request
- Poor ground connection
Diagnostic Steps
- Scan for all stored transmission codes
- Address any accompanying transmission DTCs first
- Inspect TCM-to-PCM wiring and connectors
- Verify module grounds and power supply
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ANCEL AD410 →
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✓ Autel official store
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