DTC Advanced Diagnostics: P2271
DTC P2271:Secondary Heated Oxygen Sensor (Secondary HO2S (Sensor 2)) Circuit Signal Stuck Rich

General Description

The range check during target rich operation is utilized to provide monitoring of the secondary heated oxygen sensor (secondary HO2S (sensor 2)) in order to detect deterioration of the sensor. During the enrichment of the air/fuel mixture by the active test once the target rich value has been reached, the secondary HO2S (sensor 2) voltage is monitored against rationality threshold. If the secondary HO2S (sensor 2) voltage is a specified value during the enrichment of the air/fuel mixture by the active test, the powertrain control module (PCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Once per driving cycle
Sequence
None
Duration
–
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
Time not in fuel cut-off operation
10 seconds
–
Outside air temperature
-54 °F (-48 °C)
–
Engine coolant temperature [ECT sensor 1]
-54.47 °F (-48.04 °C)
–
Catalyst temperature
842 °F (450 °C)
–
Engine speed [Engine Speed]
1,200 rpm
4,520 rpm
Barometric pressure [Baro Sensor]
739 hPa (555 mmHg, 21.8 inHg)
–
Vehicle speed [Vehicle Speed]
0 mph (0 km/h)
–
Relative air charge
13 % 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
Condition
Minimum
Maximum
Catalyst bed temperature
842 °F (450 °C)
1,562 °F (850 °C)
Exhaust gas mass flow
20 kg/h (44 lbs/h)
200 kg/h (441 lbs/h)
Commanded lambda
0.97
1.03
Other
Catalyst bed temperature is stable
[ ]: HDS Parameter

Malfunction Threshold
All of the conditions occur:
Lambda request for active test (target lean) is 1.13 or more (target lean).
Integrated exhaust gas mass flow at catalyst input after lambda request for active test is 0.08 kg (0.2 lbs) or more.
Minimum secondary HO2S (sensor 2) voltage is more than 0.2 V.

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.
Secondary HO2S (sensor 2) rich stuck

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [Engine Speed] at 3,000 rpm without load (in neutral) until the radiator fan comes on.
2.
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 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.