NA Miata Cam Angle Sensor / CAS

1.6 NA6 chain verified as B61P-18-230 -> B61P-18-230A. 1.8 NA8 verified as separate BPE8-18-230 sensor family. Do not merge NB BP4W-18-230 / ZJ10-18-221 front cam sensor into the NA CAS page; that is a 1998-2005 NB-style sensor family.

Gate 1 verified for 1990-1997 NA Miata, split by engine generation. Trap: NA CAS is an adjustable timing sensor at the back of the cam/head area; 1.6 and 1.8 are different. Common related repair is the CAS O-ring/oil leak, and timing must be checked/set after disturbance.

Checked 1.6 path: Treasure Coast Miata OE-equivalent MZ54-style CAS at $230 with a new O-ring; active eBay genuine B61P-18-230A listing at $595 plus shipping. Checked 1.8 path: RSpeed genuine BPE8-18-230 at $549.95 with 2-3-business-day ship language; Mikes used factory sensor at $85 but explicitly out of stock. Keep 1.6 and 1.8 sensor families separate.

Match 1990-1993 1.6 B61P-family versus 1994-1997 1.8 BPE8-family. Do not substitute NB front cam sensors. Replace/inspect the CAS O-ring and check ignition timing after disturbance. Diagnose belt indexing, power and grounds before condemning the sensor.

Supersede reviewed 10 unique research sources for this guide. 4 also appear above as a seller or official action and are not repeated here; 6 additional citations follow.

Research last verified 2026-07-08.

1. Mazdapartsfactor — mazda 1990 1994 mazda miata camshaft position sensor b61p18230aOpen source
2. Mazda oempartsonline — mazda engine crankshaft position sensor b61p18230aOpen source
3. Mazdapartsfactor — mazda 1994 1997 mazda miata camshaft position sensor bpe818230Open source
4. Mazdaswag — mazda engine camshaft position sensor bpe818230Open source
5. Treasure Coast Miata — i 23790787 new 94 97 miata aftermarket camshaft position sensor camshaft an...Open source
6. Forum miata — showthreadOpen source