Engine Management

Scan Tool 46 (MIL 32):

Trouble Code Number
- Scan tool 46
- General scan tool P0401
- MIL 32

Fault Message
- EGR System Failure

Background
- Once per vehicle trip the PCM monitors the EGR system flow rate.
- If the flow rate is above or below the acceptable limits, the PCM stores a diagnostic trouble code.

Range of Check
- Engine temperature is greater than 76°C (170°F)
- More than three minutes have passed since start-up.
- Engine r/min is between 1,952 and 2,400.
- MAP voltage is between 1.80 and 2.70.
- TPS voltage is between 0.6 and 1.8.
- Vehicle speed exceeds 3 mph.
- Short term fuel compensation value is exhibiting less than +4.4%
- During air/fuel ratio closed loop control

Set Condition
- The measured change in the short-term fuel compensation value shift during the test is less than 7.4% or greater than 20.5%.

Probable Cause
- EGR valve assembly failed
- EGR tube clogged
- Wiring harness and connectors failed
- Vacuum hoses failed