حساس غير مطابق مركّب على الصف

A sensor of the wrong type fitted to one bank of a V engine, so the two banks are measured differently. The engine has two of nearly everything and they are not always the same part number — upstream and downstream oxygen sensors differ, and left and right banks sometimes do too.

The module compares banks against each other, so a mismatch produces correlation and rationality codes while each sensor individually reads a plausible value. Every single-sensor test passes, which is what makes this survive a full diagnostic, and the fault only exists in the comparison.

Check the part numbers on both banks against each other and against the catalogue. A wideband sensor fitted where a narrowband belongs, or a heater of a different rating, will fit the same connector and thread. Suspect it after any sensor replacement, particularly where an aftermarket universal sensor has been fitted and spliced — that is the commonest route to two banks that no longer speak the same language.