03/06/2026 6:12 am
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Automotive Q&A
P0101 with positive trims: does the MAF reading prove the sensor is bad?
Review the evidence, add a focused answer, and distinguish confirmed measurements from assumptions.
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A 2015 Nissan Altima 2.5 sets P0101 after a steady 55 mph drive. Hot-idle airflow is 2.1 g/s, trims are +15% combined, and airflow reaches about 63 g/s during a full-load second-gear pull. Fuel pressure remains in specification. The air filter is clean and the visible intake boot is not split.
The MAF value looks low at idle, but I do not want to replace it from one number. Which checks would separate a biased sensor from unmetered air or an airflow restriction?
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04/06/2026 6:11 am
Treat grams per second as one part of a system test. Graph MAF, RPM, throttle angle, calculated load and both fuel trims through idle, snap throttle and a safe loaded pull. Then verify MAF power, ground drop and signal integrity at the sensor. Smoke-test the entire duct between the MAF and throttle, including resonators and seams that open only when the engine moves.
If trims improve when RPM rises, an air leak remains likely. If airflow stays proportionally low at load with normal manifold pressure and no restriction, then sensor bias becomes stronger evidence. Cleaning or replacement should follow the circuit and leak checks, not precede them.
Topic starter
05/06/2026 7:08 am
Smoke appeared from the lower seam of the intake resonator when the duct was flexed. After replacing that section, hot-idle airflow rose to 2.8 g/s, combined correction settled near +3%, and the loaded trace increased smoothly. P0101 did not return on the same highway route.