Possible Causes
WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.
Diagnostic Trouble Codes (DTCs) 51/B1800, 51/B1801, 51/B1802 or 51/B1803 could be caused by a short to ground, open, short or short to battery in No. 1 squib circuit, squib malfunction, spiral cable malfunction or air bag sensor assembly malfunction.
NOTE:
During testing, if DTCs other than DTC 51/B1800, 51/B1801, 51/B1802 or 51/B1803 are displayed, disregard them.