DTC P2A00

DTC P2A00:  Air Fuel Ratio (A/F) Sensor (Sensor 1) Circuit Range/Performance Problem

General Description 

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

The air/fuel ratio (A/F) sensor (sensor 1) has a linear signal output in relation to the oxygen concentration. The powertrain control module (PCM) computes the air/fuel ratio from the A/F sensor (sensor 1) output voltage and uses fuel feedback control to improve exhaust emissions. The PCM monitors the A/F sensor (sensor 1) output voltage during deceleration with the throttle fully closed, and if the output voltage deviates greatly from normal oxygen concentration levels, it detects a malfunction and stores a DTC.

NOTE:  Output to the scan tool exhibits a relationship between the A/F sensor (sensor 1) output and oxygen concentration, which is opposite to the characteristic shown in the graph. That is, a deviation toward the rich side increases the output voltage and one toward the lean side decreases the output voltage, as the stoichiometric ratio is 0.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status 

Execution	Once per driving cycle
Sequence	None
Duration	4.5 seconds or more
DTC Type	Two drive cycles, MIL on
OBD Status	PASSED/FAILED/EXECUTING/OUT OF (TEST) CONDITION

Enable Conditions 

Condition	Minimum	Maximum
Elapsed time after starting the engine	60 seconds	-
Engine coolant temperature [ECT SENSOR 1]	156 deg. F (69 deg. C)	-
Intake air temperature [IAT SENSOR (1)]	-13 deg. F (-25 deg. C)	-
Engine speed [ENGINE SPEED]	500 rpm	4, 000 rpm

[ ]: HDS Parameter

Condition	Minimum	Maximum
Vehicle speed [VEHICLE SPEED]	30 mph (48 km/h)	-
Fuel feedback	During deceleration
No active DTCs set (prevents monitor from running)	P0112, P0113, P0117, P0118, P0122, P0123, P0133, P0134, P0135, P0171, P0172, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0301, P0302, P0303, P0304, P0351, P0352, P0353, P0354, P0443, P0496, P0497, P060A, P1157, P1172, P145C, P1659, P2101, P2118, P2122, P2123, P2127, P2128, P2135, P2138, P2176, P2195, P2228, P2229, P2238, P2252

[ ]: HDS Parameter

Malfunction Threshold 

The A/F sensor (sensor 1) output voltage is 2.80 V or less, or 4.80 V or more.

Possible Cause 

NOTE:  The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• A/F sensor (sensor 1) deterioration

Confirmation Procedure 

Operating Condition 

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

• Start the engine. Hold the engine speed [ENGINE SPEED] at 3, 000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on.
• Drive the vehicle at a speed between 25 - 55 mph (40 - 90 km/h) for at least 5 minutes.
• Drive immediately at a steady speed between 55 - 75 mph (90 - 120 km/h) for at least 10 seconds.
• Decelerate with the throttle valve fully closed for at least 5 seconds.

• If the EVAP monitor runs instead of the HO2S monitor, turn the engine off, then restart it, and the HO2S monitor will restart.
• Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

With the HDS 

None.

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 and the freeze data 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, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.