Powertrain, generic · Auxiliary emission controls

P046A Catalyst Temperature Sensor 1/2 Correlation Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Some engines measure the catalyst temperature with sensors instead of only modelling it. P046A compares catalyst temperature sensors 1 and 2 of bank 1 (the side with cylinder 1): both are electrically valid, but their readings do not match – for example they differ after a long stop, or the difference does not fit the operating state. No manufacturer document available to us uses this code; FCA's EcoDiesel has only one such sensor per bank, and most makers handle exhaust temperature sensors and their correlation under EGT codes such as P0544 ff or P24C2. The description follows CARB's plausibility requirement for input components.

Likely causes

One of the two sensors drifting (soot on the tip, ageing)
Sensors fitted or connected the wrong way round
Contact resistance at one sensor's connector
Exhaust leak between the sensors

Symptoms

  • Check engine light on
  • Usually no change in driving
  • Diesel: filter regeneration possibly changed

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

catalyst temperature sensor b1s1catalyst temperature sensor b1s2sensor wiringengine control module

Related codes

P046BP0426P042BP0425P042A

References: law.cornell.edu, hella.com, static.nhtsa.gov.