P0068

DTC P0068

CIRCUIT DESCRIPTION
The engine control module (ECM) uses the following information to calculate an expected airflow rate:
- The throttle position (TP)
- The barometric pressure (BARO)
- The intake air temperature (IAT)
- The engine RPM

If the ECM detects the airflow rate is more than expected, DTC P0068 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0068 Throttle Body Airflow Performance

CONDITIONS FOR RUNNING THE DTC
- DTCs P0641, P0651, P1516, P2101, P2119, P2176 are not set.
- The engine is running and the engine speed is more than 600 RPM.
- DTC P0068 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The ECM detects that the calculated airflow rate is more than expected.
- The above condition is present for more than 0.2 second.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
- A message center or an indicator displays Reduced Engine Power.
- Under certain conditions the control module commands the engine OFF.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
- The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
- The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
- Inspect for the following conditions:
- The throttle blade for damage
- A skewed cam sensor signal-Inspect for signals that are intermittently shorted to ground, causing a fluctuating RPM on the scan tool.
- If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

TEST DESCRIPTION

Step 1 - Step 7:

Step 8 - Step 9:

The numbers below refer to the step numbers on the diagnostic table.
5. This step will determine if the manifold absolute pressure (MAP) sensor voltage is within the proper range at idle.
6. This step will determine if the MAP sensor responds properly to the change in manifold pressure.
7. A throttle blade that sticks or binds may set this code. Opening the throttle through the entire range will indicate conditions such as these.
9. When the ECM detects a condition within the ETC system, other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.