GM 19 Crankshaft Sensor Circuit Fault
How to read it
Code 19 reads as 1 flash, pause, 9 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 19 mean?
Crankshaft Sensor Circuit Fault
Common causes of 19
- Failed crankshaft position sensor
- Damaged sensor wiring near the crank pulley
- Corroded connector or poor sensor ground
- Excessive air gap from a loose sensor bracket
How to fix 19
- Retrieve codes with a paperclip across ALDL pins A and B and note related codes
- Check for spark and injector pulse to confirm a missing crank signal
- Inspect wiring and connector for chafing and corrosion
- Test sensor resistance and output per the service manual
- Replace the sensor only after wiring and air gap check good
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 19. Include your vehicle, the issue and a source if you have one.