The ECM provides a pulse width modulated control circuit to adjust the current through the heater The HO sensor heater circuit uses a relay on the B side of the circuit

Reference (System Diagram of Sensor 2):

from Battery

EFI MAIN

Ground

HO2 Sensor

Heater

HT1B

HT1B

OX1B

OX1B

EX1B

MREL

A133556EG5

DTC No.

DTC Detection Condition

Trouble Area

PGG37

Heated Oxygen (HO2) sensor heater current less than 0.3 A (1 trip detection logic)

• Open in HO2 sensor heater circuit

• ECM

PGG38

Heated Oxygen (HO2) sensor heater current more than 2 A (1 trip detection logic)

• Short in HO2 sensor heater circuit

• ECM

PG141

Cumulative heater resistance correction value exceeds threshold

(2 trip detection logic)

• Open or short in HO2 sensor heater circuit

• ECM

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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