C0046

C0046 is the mirror-image of C0041 on the right rear wheel — generic fault in the RR wheel speed sensor circuit, signaling that the EBCM is not seeing the expected signal from the RR WSS during wheel rotation. Cheapest-first ladder is identical to C0041: (1) Lift the vehicle, spin the RR by hand at ~1 rev/sec, and watch live data. Passive WSS should produce 0.4-1.5V AC building with speed; active Hall-effect WSS should produce a 0.2-1V DC square wave with frequency climbing as the wheel spins. Compare against the LR signal — if the LR is healthy and the RR is flat, the fault is isolated to the RR circuit. (2) DMM-check passive sensor resistance at the connector (1,000-2,500 ohms typical; open or shorted is a dead sensor). Back-probe active sensors for the supply and signal voltages key-on. (3) Inspect the harness from sensor to body grommet — on most rear-axle layouts the RR runs along the differential housing or trailing arm and is exposed to the same rust and rub-through hazards as the LR. (4) Pull and visually inspect the sensor tip and tone ring; measure air gap if accessible. Expensive-misdiagnosis caveat: GM trucks 1999-2007 — the ABS tone ring on the right rear CV axle (4WD) or rear axle shaft (2WD) rusts off the same way as the left rear, leaving a clean stub of axle and an infinite air gap. The sensor is fine; the fix is the axle or a slip-on repair tone ring, not a new $80 WSS that does nothing for a missing ring.

Vehicle-specific patterns: 1999-2007 GM trucks (Silverado/Sierra/Tahoe/Yukon/Suburban) with the Kelsey-Hayes 325 EBCM throw C0046 from rusted-off tone rings on the rear axle, corroded sensor connectors at the harness junction near the differential, and water-damaged EBCM internals — visual ring inspection is step one before any sensor purchase. 1997-2014 Ford F-150 with rear hub-mounted WSS throws C0046 from failed rear hub bearings that destroy the integrated encoder ring; the fix is the full $180-$300 hub assembly. 2008-2014 Dodge Caravan/Town & Country throws C0046 from the same trailing-arm harness rub-through pattern as C0041, just on the passenger side. 2002-2009 Subaru Outback/Forester throws C0046 from corroded RR knuckle-mounted sensor bolts that seize and break the sensor on removal. Estimated repair: $80 to $450.