Acura RL. Manual - part 11



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.

Diagnosis Details

Conditions for illuminating the MIL

When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the PCM
memory. If the malfunction recurs during the next (second) drive cycle, the MIL comes on and the DTC and
the freeze frame data are stored.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool
Clear command or by disconnecting the battery.

DTC P0154 (152): ADVANCED DIAGNOSTICS

DTC P0154: FRONT AIR/FUEL RATIO (A/F) SENSOR (BANK 2, SENSOR 1) HEATER SYSTEM
MALFUNCTION

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics - RL

Friday, June 05, 2009 2:32:03 PM

Page 41

Fig. 32: Front Air/Fuel Ratio Sensor (Bank 2, Sensor 1) Heater System Malfunction Determination

General Description

The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is activated by warming the element with the heater
any by maintaining it at a steady high temperature to accurately calculate the air/fuel (A/F) ratio. The front
A/F sensor does not become active when the element is not properly heated due to a heater malfunction, and
the exhaust emissions deteriorate. The powertrain control module (PCM) monitors the front A/F sensor
internal resistance.

1. When the front A/F sensor does not activate within a set time after the front A/F sensor heater starts to

warm up (with high front A/F sensor internal resistance), a malfunction of the front A/F sensor heater
is detected, and a DTC is stored.

2. When the front A/F sensor heater cycles ON and OFF within a set time, and the resistance remains

high when the heater is ON, a malfunction in the front A/F sensor heater is detected, and a DTC is
stored.

Because the effect engine control differs according to the front A/F sensor internal resistance, there
are two types of malfunction detection threshold levels. When either one is reached, a malfunction is
detected.

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

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics - RL

Friday, June 05, 2009 2:32:03 PM

Page 42

MONITOR DESCRIPTION CHART

Enable Conditions

ENABLE CONDITIONS

Malfunction Threshold

Malfunction determination 1

The front A/F sensor (bank 2, sensor 1) heater internal resistance value is 110 ohms or more for at least 40
seconds right after the engine starts.

Malfunction determination 2



The front A/F sensor (bank 2, sensor 1) heater internal resistance value is 110 ohms or more for at
least 15 seconds.



The front A/F sensor (bank 2, sensor 1) heater internal resistance value is 200 ohms or more for at
least 1 second.

Driving Pattern

Start the engine, and let it idle for at least 2 minutes.

Diagnosis Details

Conditions for illuminating the MIL

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool
Clear command or by disconnecting the battery.

Execution

Continuous

Sequence

None

Duration

40 seconds or more

DTC Type

Two drive cycles, MIL ON

OBD Status

PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Condition

Minimum

Maximum

Battery voltage 10.5 V

Fuel feedback

Other than during fuel cut-off operation

No active DTCs P0155, P1174, P2197, P2240, P2241, P2247, P2249, P2254, P2255, P2630, P2631

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics - RL

Friday, June 05, 2009 2:32:03 PM

Page 43

DTC P0155 (152): ADVANCED DIAGNOSTICS

DTC P0155: FRONT AIR/FUEL RATIO (A/F) SENSOR (BANK 2, SENSOR 1) HEATER CIRCUIT
MALFUNCTION

Fig. 33: Front Air/Fuel Ratio Sensor (Bank 2, Sensor 1) Heater - Circuit Diagram

General Description

The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold, and it detects
oxygen content in the exhaust gas. The front A/F sensor outputs voltage to the powertrain control module
(PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F
sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion
layer, and the heater, and it enables overall feedback control. The heater is controlled by the PCM and is
energized when the sensor element temperature is low. It heats the sensor to stabilize the detection of
oxygen content. The PCM monitors the front A/F sensor heater output (return check). A malfunction is
detected if the return signals do not meet the command value (for heater activation) in the PCM for a set
time or more and a DTC is stored.

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

MONITOR DESCRIPTION CHART

Execution

Continuous

Sequence

None

Duration

2 seconds or more

DTC Type

One drive cycle, MIL ON

OBD Status

PASSED/FAILED/NOT COMPLETED (STILL TESTING)

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics - RL

Friday, June 05, 2009 2:32:03 PM

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