DTC Advanced Diagnostics: P2097 (1.5L Engine)
DTC P2097: Post Catalyst Fuel Trim System Too Rich
General Description
The powertrain control module (PCM) detects oxygen content in the exhaust gas by the air/fuel ratio (A/F) sensor (sensor 1), and it uses feedback control before the three way catalytic converter (TWC) to bring the air/fuel ratio close to the target air/fuel ratio. The target air/fuel ratio is adjusted by the secondary heated oxygen sensor (secondary HO2S (sensor 2)) output so that the air/fuel ratio in the TWC is optimized. When the A/F sensor (sensor 1) cannot measure air/fuel ratio in the exhaust gas normally, a gap occurs to the actual air/fuel ratio. As a result, the gap causes a deviation in target air/fuel ratio control (after TWC) which is determined by the secondary HO2S (sensor 2). If the deviation exceeds a limit, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Once per driving cycle* |
| Sequence | None |
| Duration | Depending on the driving conditions |
| DTC Type | Two drive cycles, MIL on |
*: The malfunction judgment is cleared when it is judged as normal under the same driving conditions in which the malfunction is detected.
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Engine coolant temperature [ECT Sensor 1] | 155.9 deg.F (68.8 deg.C) | - |
| Intake air temperature [IAT Sensor (1)] | 18.9 deg.F (-7.3 deg.C) | - |
| Engine speed [Engine Speed]* 1 | 550 rpm | - |
| Engine speed [Engine Speed]* 2 | 720 rpm | - |
| Intake air amount | 8.0 g/s (0.283 oz/s) | - |
| Fuel feedback | Closed loop | |
*1: CVT
*2: M/T
[ ]: HDS Parameter
Malfunction Threshold
Either of the conditions is met:
- Short term fuel trim is higher than -0.0022.
- Long term fuel trim is higher than 0.048.
Possible Cause
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) malfunction/slow response
- A/F sensor (sensor 1) circuit range/performance
- Fuel system too lean
- Fuel system too rich
- Secondary HO2S (sensor 2) circuit signal stuck lean
- Secondary HO2S (sensor 2) circuit open
- Secondary HO2S (sensor 2) slow response
- Air/fuel ratio variation between cylinders
- Misfire
- Exhaust system failure (exhaust gas leak)
Confirmation Procedure
Operating Condition
- 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, then let it idle.
- Drive at a steady speed between 15 - 75 mph (25 - 120 km/h) for at least 63 seconds.
- When freeze data or the on-board snapshot is stored, drive the vehicle under those conditions instead of Driving Pattern step 2.
- 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.