DTC 29
Data Trouble Code No. 27 - Sub Heated Oxygen Sensor Signal - LeftDetecting Condition
Main Heated Oxygen Sensor signal is 0.45 volts or more and Sub Heated Oxygen Sensor signal is 0.45 volts or less under the following conditions (2 trip detection);
- Engine coolant temperature 80°C (176°F) or more.
- Accelerator pedal fully depressed for 2 seconds or more.
Trouble Area
- Open or short in Sub Heated Oxygen Sensor circuit.
- Sub Heated Oxygen Sensor.
- Engine Control Module.
Malfunction Indicator Lamp
Normal Mode On
Test Mode On
Code 27 And 29 Description:
Circuit description
The oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust gas and provide feedback to the computer for control of the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen sensor informs the engine control module of the LEAN condition (small electromotive force: 0 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the exhaust gas is reduced and the oxygen sensor informs the engine control module of the RICH condition (large electromotive force: 1 V).
The engine control module judges by the electromotive force from the oxygen sensor whether the air-fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor causes output of abnormal electromotive force, the engine control module is unable to perform accurate air-fuel ratio control.
DTC Detection Pattern:
DTC Detection Driving Pattern
Code 27 And 29 Diagnostic Chart:
Diagnostic Chart
Code 27 And 29 Circuit Diagram:
Circuit Diagram