P0AF5

P0AF5 sets when the BMS sees the voltage-sense "C" circuit reporting ABOVE the expected range — typically above 4.5V on a Li-ion sense input or above ~8.5V on a NiMH stick input — which the controller interprets as a shorted-to-high-voltage or open-circuit condition on the sense lead. The cheapest-first ladder: scan-tool per-module voltages and look for the group reporting absurdly high (a sense lead that's open often floats up to rail voltage at the BMS input). Cross-check against pack-level voltage at the service plug after the safety lockout procedure — if pack voltage matches the sum of the other modules but one input is reading high, the sense lead is open, not the module. Inspect the BMS connector for pushed-out pins or a corroded socket where pin contact has been lost. Per-cell Li-ion should sit 3.6-4.2V (4.2V is full charge, 3.0V is the lower discharge limit, 2.5V is permanently damaged); NiMH per-stick is 7.2V nominal, 8.4V at full charge. HV pack voltage sense reads 200-650V scaled at the controller depending on platform. DO NOT probe HV orange-wire circuits with a standard multimeter. Always service HV with Class 0 1000V gloves, isolation tester (Megger), and DC-rated lugged probes. Voltage-sense codes (P0AF3-P0AF7) often indicate the BMS sense lead chafed at the bus-bar bolt — re-tightening with new lockwasher can fix without pack replacement.

Vehicle-specific patterns: 2004-2009 Toyota Prius Gen2 throws P0AF5 most often from an open sense lead at the ring terminal — corrosion cracks the copper terminal at the crimp, the lead disconnects, and the BMS input floats high. A re-terminate with a fresh ring lug and proper crimp is the fix. 2010-2015 Prius Gen3 shows the same pattern plus a documented BMS connector socket-tension issue where the female pin loses spring tension after repeated service. 2011-2015 Chevy Volt Gen1 throws P0AF5 after a Voltec service where the LBC was disconnected and reconnected without verifying pin engagement. 2017-2019 Bolt EV throws P0AF5 from the LG cell-module pack as a high-side complement to the more common P0AF4 — both are recall territory. 2016-2021 Mercedes-Benz hybrid (S550e, GLC350e, E350e) throws P0AF5 from a known sense-harness issue at the pack bulkhead on the P2 hybrid architecture. Estimated repair: $180 (re-terminate sense lead) to $1,800 (BMS connector replacement) to $15,000+ (full pack on a Bolt or Mercedes plug-in).