Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
EGR Monitor
This monitor applies to DTC P0401. Following conditions must be met during the test:
- Engine coolant temperature must be 176°F (80°C) or more.
- Atmospheric temperature is 41°F (5°C) or more.
- Selector lever is in "D" range (A/T).
- A/C switch is off.
Monitor takes about 10 minutes to complete. To run monitor, use illustration. See Fig 1 . Perform steps as follows:
- Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
- After engine is completely warmed up, turn ignition off.
- Start engine and quickly accelerate vehicle to 35-40 MPH.
- Keep speed constant at 35-40 MPH for 20 seconds or more. Use 4th gear on M/T.
- Decelerate by closing throttle fully and allowing engine speed to drop from 2000-3000 RPM to about 900 RPM. DO NOT apply brakes. DO NOT turn steering wheel or operate light switch during this time.
- Accelerate to 35-40 MPH, then hold speed constant for 20 seconds or more. Repeat steps 4 and 5 seven more times.
- Return vehicle to shop and turn ignition off. Recheck for DTC(s). If any DTC(s) is set, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.