Reverse Output Circuit Malfunction
The P0813 code indicates a problem in the reverse output circuit, which is responsible for signaling the transmission control module (TCM) that reverse gear is selected. This circuit typically involves a switch or sensor on the transmission that sends a voltage signal to the TCM. When the TCM detects an incorrect or missing signal, it sets this code. Common causes include a faulty reverse switch, damaged wiring, or a malfunctioning TCM. This issue can prevent the vehicle from engaging reverse gear or cause the reverse lights to malfunction.
01. Most Common Causes
- Faulty reverse switch/sensor
- Damaged or corroded wiring/connectors
- Blown fuse or relay
- Malfunctioning transmission control module (TCM)
02. Symptoms You Will Notice
- Reverse lights not working
- Transmission stuck in park or unable to shift into reverse
- Check Engine Light illuminated
- Erratic transmission behavior
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and verify P0813 is present.
Step 2: Inspect reverse light operation; if lights don't work, check fuse and bulbs.
Step 3: Locate the reverse switch (usually on transmission) and test its continuity with a multimeter.
Step 4: Check wiring and connectors for damage, corrosion, or loose connections.
Step 5: If wiring and switch are okay, test the TCM for proper signal reception.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code, as it may cause the transmission to not engage reverse gear, leaving you stranded. Additionally, reverse lights may not work, posing a safety risk.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause. A reverse switch replacement is usually inexpensive, while TCM repairs can be more costly.