Let's talk about the KEYOPO Engine Speed Sensor (4327233) – a part that promises compatibility with Cummins ISB/QSB engines. I installed this on a mid-2000s Cummins rig, and here's the real-world scoop.

The good first: It's impressively compact and lightweight, making installation in tight engine bays noticeably easier than bulkier OEM sensors. During normal operation, the working unit provided crisp tachometer signals without the erratic jumps I've seen with some aftermarket sensors. The matte black housing also blends well with engine components – a small but appreciated detail.

Now the concerning part: Like another reviewer, I experienced a DOA (dead on arrival) unit in my two-pack order. The faulty sensor showed zero signal output right out of the box, which was frustrating during what should have been a quick swap. This quality control issue makes me hesitant to fully recommend buying multiple units at once despite the cost savings.

When it works though? Performance is solid. Over three months of daily driving through everything from city traffic to mountain grades, the functioning sensor maintained accurate RPM readings even during heavy load changes. Just be sure to test each unit immediately – that 6-month warranty won't help if you discover the issue months into installation.