P061B: How to Diagnose & Fix — Internal Control Module Torque Calculation Performance

Naturally aspirated Skyactiv-G CX-5s from the 2018-2019 model years — the bulletin also covers the Mazda6 of the same period and explicitly excludes the Skyactiv-G 2.5T — store P061B:00 in two reproducible situations. The first is an interrupted crank: if the driver lets go of the brake pedal partway through starting, the start sequence is interrupted and the PCM's torque model briefly loses its reference. The second is acceleration through the 1300-1600 rpm band at wide-open throttle, where torque rises very quickly and the calculated-versus-commanded comparison momentarily exceeds the allowed margin. Mazda's own analysis is blunt about the cause: improper PCM control logic made the engine torque calculation error detection too sensitive, so the module flags a fault that does not correspond to any real mechanical or sensor problem. The consequence for the driver is nonetheless real — the PCM turns on fail-safe mode and reduces engine rpm, so the complaint arrives at the shop as 'lack of power with the check engine light on': the car will drive, but it will not pull, and the condition often shows up first on a highway on-ramp or when passing. Mazda published the fix as bulletin 01-008/22 (NHTSA document 10218722). Because the trigger is a driving pattern rather than a component, the fault can go months without repeating and then set twice in a week, which frequently leads shops to chase MAF sensors, throttle bodies and even transmissions on a vehicle that needs nothing but a calibration.

The drive-by-wire electronic throttle body (ETB) develops an internal electronic/motor fault (not just dirt) that causes the powertrain control module to command reduced power. The car drops into limp mode with a wrench/powertrain-malfunction light, often storing throttle-position or actuator-control codes.

Early CX-50s built before Mazda revised the engine control software set P061B:00 in two very specific situations: shortly after a cold start, and when the vehicle is operated at high elevation — Mazda's bulletin cites altitudes higher than 3,000 m / 10,000 ft. In both cases the air the engine actually ingests differs from what the PCM's torque model expects. On a cold engine the enrichment, idle-up and spark retard used for catalyst light-off change the relationship between airflow and produced torque; at altitude the reduced air density does the same thing. Mazda's shipped control logic did not compensate correctly, so the module's internal torque-plausibility comparison exceeded its threshold and latched a fault. Because this monitor is treated as a torque-safety supervisor, the PCM responds by pulling timing and clamping the throttle, and the driver gets a check engine light together with a very obvious lack of power until the code is cleared or the key is cycled. Mazda addressed the cold-start half first in bulletin 01-015/22 (November 2022, NHTSA 10226823) for early-production CX-50s, then issued 01-011/23 (December 2023, NHTSA 10248340) after the same monitor was found to trip at high elevation; for US/Canada-spec vehicles that later bulletin covers 2023 CX-50s built before September 27, 2022 (it extends to 2023-2024 only for Mexico-spec units). Mazda is explicit that this is a false detection caused by improper PCM control software, not an actual engine failure.

2019 Ram 2500 and 3500 pickups with the 6.7L I6 Cummins — both the standard Turbo Diesel and the High Output Turbo Diesel — can set P061B-00 among the long list of faults addressed by a PCM calibration update. Stellantis addressed the pattern in service bulletin 18-066-23 (Group 18, Vehicle Performance; NHTSA document 10239975). The customer complaint is simply an illuminated malfunction indicator lamp; on scan, the technician finds one or more of the more than 40 DTCs the bulletin lists, including P061B-00 Internal Control Module Torque Calculation Performance, P0299-00 Turbocharger Underboost, P0461-00 Fuel Level Sensor 1 Performance and P0506 Idle Control System RPM Lower Than Expected. The grouping is the diagnostic clue: on a diesel the PCM builds its torque estimate from commanded rail pressure, injection quantity and boost, so a calibration that models variable-geometry turbo boost response too optimistically will produce both an underboost complaint and a torque-plausibility complaint from the same event. Drivers typically notice little more than the lamp, though some report a soft spot in throttle response or a brief reduction in power under heavy load or while towing. What makes this case worth recognizing is what it rules out: on a truck still on pre-update software, P061B here is very often a calibration artifact rather than evidence of a failing turbo actuator, a leaking charge-air cooler or a dying PCM — all of which are expensive parts that get replaced on these trucks for exactly this code.

Due to improper programming of the fuel injection electronic control unit (FI-ECU), sudden changes in throttle opening could turn on the check engine light and/or make the engine lose drive power, hesitate or stall. Supplier Denso told Honda the correction control logic for air flow rate and fuel injection volume was set improperly. Certain 2023-2025 Honda Pilot built September 13, 2022 to January 9, 2025 (also Acura MDX Type-S and TLX Type-S). Eligibility is by VIN.