P24F4
NOx Sensor Delayed Response - High to Low Bank 1 Sensor 1
What it means
The pre-catalyst NOx sensor on bank 1 (sensor 1) reacts too slowly when NOx in the exhaust drops from a high to a low level — for example after a fuel cut or transition into low-load. Aged ceramic cells, soot deposits or condensation inside the sensor protective tube slow the diffusion of NOx to the measuring element.
Is it safe to drive?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Aged sensor element with reduced response speed
highOne of the most commonly reported causes for this code — check this first.
Soot clogging the protective tube
mediumA plausible cause — test and verify before replacing parts.
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