Toyota 2GR-FE Manual page 273

DTC No.
P0032 Air-Fuel Ratio (A/F) sensor heater (bank 1, 2, sensor 1)
P0052 current is more than 10 A (1 trip detection logic)
HINT:
• Bank 1 refers to the bank that includes cylinder No. 1.
• Bank 2 refers to the bank that does not include cylinder No. 1.
• Sensor 1 refers to the sensor closest to the engine assembly.
• Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
1. The ECM uses information from the Air-Fuel Ratio (A/F) sensor to regulate the air-fuel ratio and keep it
close to the stoichiometric level. This maximizes the ability of the Three-Way Catalytic Converter
(TWC) to purify the exhaust gases.
2. The A/F sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM.
The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor
element is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and
includes an integrated heating element.
3. The zirconia element generates a small voltage when there is a large difference in the oxygen
concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage
generation.
4. The A/F sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor
cannot generate useful voltage signals without supplementary heating. The ECM regulates the
supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater
element. If the heater current is outside the normal range, the signal transmitted by the A/F sensor will
be inaccurate, as a result, the ECM will be unable to regulate air-fuel ratio properly.
5. When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets
this as a malfunction in the sensor heater and sets a DTC.
Example:
The ECM sets DTC P0032 or P0052 when the current in the A/F sensor heater is more than 10
A. Conversely, when the heater current is less than 0.8 A, DTC P0031 or P0051 is set.
MONITOR STRATEGY
Related DTCs
Required sensors / components (Main)
Required sensors / components (Sub)
Frequency of operation
Duration
MIL operation
Sequence of operation
TYPICAL ENABLING CONDITIONS
All:
Monitor runs whenever following DTCs are not present
P0031 and P0051:
Battery voltage
Heater output duty
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
DTC Detection Condition
• Short in A/F sensor heater (bank 1, 2, sensor 1)
circuit
• A/F sensor heater (sensor 1)
• A/F HTR relay
• ECM
P0031: A/F sensor heater (bank 1) open/short (Low electrical current)
P0032: A/F sensor heater (bank 1) open/short (High electrical current)
P0051: A/F sensor heater (bank 2) open/short (Low electrical current)
P0052: A/F sensor heater (bank 2) open/short (High electrical current)
A/F sensor heater (bank 1 and 2)
-
Continuous
10 seconds
Immediate
None
P0300 - P0306 (misfire)
10.5 V or more
50 % or more
ES–117
Trouble Area
ES