DTC Advanced Diagnostics: P0133 (2.0L Engine) (2024 2025)

DTC P0133  : Air Fuel Ratio (A/F) Sensor (Sensor 1) Malfunction/Slow Response

General Description 

Courtesy of HONDA, U.S.A., INC.

The powertrain control module (PCM) monitors the air/fuel ratio (A/F) sensor (sensor 1) for slow response malfunctions. Aging and contamination of the A/F sensor (sensor 1) can slow down the sensor response rate. A dynamically slow signal can lead to increased exhaust emissions. When enable conditions are met and catalyst is purged with the rich mixture (rich conditioning phase), the monitor switches to the lean mixture where the measurement of catalyst oxygen storage capacity is carried out (oxygen storage capacity (OSC) measurement). At the beginning of this state the delay time values as well as the gradients of A/F sensor (sensor 1) signal are evaluated (rich-to-lean transition). After OSC measurement is finished a rich operation state is commanded. At the beginning of this state the delay time values as well as the gradients of A/F sensor (sensor 1) signal are evaluated (lean-to-rich transition). If the delay time or transition time is a specified value, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type 

Execution	Once per driving cycle
Sequence	None
Duration	0.5 seconds or more
DTC Type	Two drive cycles, MIL on

Enable Conditions 

Step response measurement 

Condition		Minimum	Maximum
Time not in fuel cut-off operation		10 seconds	-
Outside air temperature		-54 deg.F (-48 deg.C)	-
Engine coolant temperature [ECT sensor 1]		-54.47 deg.F (-48.04 deg.C)	-
Catalyst temperature		842 deg.F (450 deg.C)	-
Engine speed [Engine Speed]		1, 200 rpm	4, 520 rpm
Vehicle speed [Vehicle Speed]		0 mph (0 km/h)	-
Relative air charge		15 % to 22 %	-
Other		Exhaust gas mass flow is stable for at least 1 second
		Actual secondary HO2S (sensor 2) heater temperature is around set point temperature
		Following table A must be met for more than 0.08 kg (0.18 lbs) of integrated exhaust gas mass flow
		Canister not purging

Table A for step response measurement 

Condition		Minimum	Maximum
Catalyst bed temperature		842 deg.F (450 deg.C)	1, 562 deg.F (850 deg.C)
Exhaust gas mass flow* 1		30 kg/h	200 kg/h
Exhaust gas mass flow* 2		20 kg/h	200 kg/h
Commanded lambda		0.97	1.03
Other		Catalyst bed temperature is stable

*1: USA/Canada models

*2: Mexico models

Identification 

Condition		Minimum	Maximum
Elapsed time after starting the engine		7 seconds	-
Elapsed time after the A/F sensor (sensor 1) is active		10 seconds	-
Time not in fuel cut-off operation		3 seconds	-
Time not gear shifted		0.15 seconds	-
Time lambda closed control		2 seconds	-
Vehicle speed [Vehicle Speed]		0 mph (0 km/h)	-
Rate of change of modeled lambda		0.02	-
Other		No transition time faults are detected during step response measurement

[ ]: HDS Parameter

Malfunction Threshold 

Any of the conditions is met:

• Step response measurement
• • -

    The average value of delay time in lean-to-rich direction is more than 0.5 seconds at least 3 fault confirmations.

• • -

    The average value of delay time in rich-to-lean direction is more than 0.5 seconds at least 3 fault confirmations.

• • -

    The average value of transition time in lean-to-rich direction is greater than 0.5 seconds at least 3 fault confirmations.* 1

• • -

    The average value of transition time in rich-to-lean direction is greater than 0.5 seconds at least 3 fault confirmations.* 1

• Identification
• • -

    The delay time in lean-to-rich direction is more than 1 second.

• • -

    The delay time in rich-to-lean direction is more than 1 second.

• • -

    The transition time in lean-to-rich direction is more than 1 second.

• • -

    The transition time in rich-to-lean direction is more than 1 second.

• • -

    The sum of delay and transition time in lean-to-rich direction is more than 1 second.

• • -

    The sum of delay and transition time in rich-to-lean direction is more than 1 second.

Possible Cause 

Confirmation Procedure 

Operating Condition 

• Start the engine. Hold the engine speed [Engine Speed] at 3, 000 rpm without load (in neutral) until the radiator fan comes on.
• Drive the vehicle at constant vehicle speed with part load.

• Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details 

Conditions for setting the DTC 

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC, the freeze data, and the on-board snapshot are stored.

Conditions for clearing the DTC 

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.