GM 63 Right Bank O2 Sensor Circuit Open
How to read it
Code 63 reads as 6 flashes, pause, 3 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.
New to flash codes? The How to Read GM OBD-I Codes with a Paperclip walks through the test and what the numbers mean. The general OBD-I guide covers the rest.
What does GM code 63 mean?
Right Bank O2 Sensor Circuit Open
Common causes of 63
- Failed right bank O2 sensor
- Open sensor signal wire
- Corroded O2 connector
- Exhaust leak near the sensor
How to fix 63
- Read codes with a paperclip jumper and confirm code 63 repeats
- Inspect the sensor wiring for burns on the exhaust
- Check the connector for corrosion and loose pins
- Watch sensor voltage on a scan tool and look for switching
- Fix exhaust leaks ahead of the sensor
- Replace the sensor only after wiring tests clean
Source
Qualified source review
Sources and review
Review: qualified. Read the source limits below.
- GM and Chevrolet OBD1 Trouble Codes (ALDL Fault Code List)
live reference page (troublecodes.net)
Supports: code identity and GM meaning
Fetched directly. Single publisher, so the record is qualified, not verified. Causes and check order are curator-written from the circuit the code names.
https://www.troublecodes.net/gm/
Last updated 2026-09-19.
Report a correction for 63. Include your vehicle, the issue and a source if you have one.