Powertrain, generic · Auxiliary emission controls

P0437 Catalyst Temperature Sensor Circuit Low Bank 2 Sensor 1

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Some engines – mainly diesels – measure the temperature at or in the catalyst with a thermistor in a voltage divider instead of only modelling it; most makers report exhaust temperature sensors under P0544 ff, P2031 ff or P2080 ff instead. Sensor 1 of bank 2 is the first catalyst temperature sensor on the side without cylinder 1. P0437 means the signal voltage is below its lower limit – typically the signal wire is shorted to ground or the sensor is shorted internally. No manufacturer document available to us uses this code; the description follows CARB, which requires input circuits to be checked for circuit faults and plausibility, and the comparable exhaust temperature sensors.

Likely causes

Signal wire shorted to ground (chafed)
Sensor shorted internally
Water or corrosion in the connector
Engine module

Symptoms

  • Check engine light on
  • Usually no noticeable change (substitute value from the model)
  • Diesel: filter regeneration distorted or blocked, possibly further codes such as P2459 or P0420

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–300
Time0.5–1.5 h

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

Parts involved

catalyst temperature sensor b2s1sensor wiringengine control module

Related codes

P0435P0436P0427P043CP0547P0430

References: law.cornell.edu, hella.com, gsi.ext.gm.com.