Powertrain, generic · Auxiliary emission controls
P0432 Catalyst 2 Efficiency Below Threshold Bank 2
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
Catalyst 2 is the second catalyst in the flow direction of bank 2 (the side without cylinder 1) – the main or underfloor catalyst behind the close-coupled one; the older wording was Main Catalyst. P0432 means it no longer converts enough. No manufacturer document available to us uses this code; it would apply to engines with two exhaust lines and a close-coupled and a main catalyst on each. The description follows CARB, which requires the conversion of all monitored catalysts to be checked, and the bank 1 counterpart P0422.
Likely causes
Main or underfloor catalyst aged or poisoned
Diesel: exhaust fuel injector coked, doses too little
Temperature or oxygen sensor after the catalyst wrong
Misfire or mixture fault as prior damage
Symptoms
- Check engine light on
- Emission test problems
- Diesel: possibly more frequent filter regenerations
Repair estimate
DifficultyMediumWorkshop job
Parts and labour€400–2,500
Time1–3 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
underfloor catalystexhaust temperature sensorengine control module
Related codes
References: law.cornell.edu, gsi.ext.gm.com.