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Forum > Consumer Assistance > Question

How to Complete a 2004 PT Cruiser OBD-II Drive Cycle

I guess my basic question is how many miles do I need to drive in order to reset the ECM on my 2004 PT Cruiser. I took the vehicle for a smog test and I was told that I have to drive it for 200 miles for ECM to reset after battery replacement. I should also mention that the ECM was replaced with a refurbished unit. My regular mechanic said drive for 100 miles, so I would like your opinion. Thank you.
Answer:

In most cases, all the emission monitors should run during normal vehicle operation over the course of 200 to 300 miles. However, due to different driving habits, the criteria required to run a monitor may not always be met. Following the PT Cruiser drive cycle below should allow the emission monitors to complete. The drive cycle must be followed accurately. Take extra caution when performing the drive cycle on public roadways. Perform the drive cycle at your own risk. If you feel you might not be able to perform the drive cycle safely, or obey all traffic laws, seek the assistance of a smog check repair station which will be able to perform the drive cycle on a dynamometer, utilizing specialized OBD II drive cycle readiness tools/scanner/computer.

Your Chrysler PT Cruiser must have all of its emission monitors READY or COMPLETE in order to pass the smog test, except for the EVAP monitor (as of the time of this writing). Emission monitors (also known as Readiness Flags) are internal self tests which your vehicle's ECU (engine control unit) conducts to ensure its emission systems are working properly. Typically driving 200-300 miles in both city and highway traffic conditions is sufficient to complete the emission monitors. However at times, a vehicle owner's driving patterns do not match those required for the emission monitors to run; and performing the drive cycle's specific driving pattern is required.

Replacing the battery or even having simply disconnected the battery on your PT Cruiser caused the engine control module (ECM) to reset and subsequently clear all the emission monitors (and trouble codes; if any existed). Your Cruiser's engine control module performs internal self-tests in order to ensure the engine is running efficiently and not polluting. The entire process of self-testing various emission control systems is called a Drive Cycle.

As mentioned above, typically driving 200-300 miles through various traffic conditions and over the course of a few days is enough to get the drive cycle to initiate; and readiness monitors to become READY or COMPLETE. At times however simply driving an extend length of time does not make the monitors complete. We're going to recommend following the drive cycle indicated below. Please ensure at all times during the drive cycle that the fuel tank is between 15% to 75% full. Certain monitors will not run if the tank is near empty or full.

How to Perform Drive Cycle for PT Cruiser

Your vehicle will need to be parked for at least an hour and then restarted. This is required to set the EVAP monitor. We recommend leaving the vehicle parked overnight. In total, it will take to drive trips to complete all monitors.

Catalyst Monitor Drive Trace

Pre-Conditioning Requirements:

- MIL must be off.

- No DTCs present.

- Fuel level is between 15% and 85% full.

- ECT above 70º F.

- Engine must have run at least 90 seconds

- Engine between 1,350 & 1,900 rpm.

EGR System Monitor Drive Trace - Vacuum controlled

Pre-Conditioning Requirements:

- MIL must be off.

Driving Procedure

1) Idle vehicle for five minutes (to reach normal engine operating temperature and closed loop operation).

2) Drive with a steady vehicle speed between 40 & 60 mph for 8 minutes.

EGR System Monitor Drive Trace - Electronic

Pre-Conditioning Requirements:

- MIL must be off.

- MAP must be between 0-60 KPa.

- Engine speed between 500-850 rpm.

- ECT is above 180º F (90º C).

- No misfire pending or matured fault should be present.

- A/C clutch, PS Switch and Cooling fans do not change state (turn off).

Driving Procedure

1) Idle vehicle for five (5) minutes (to reach normal engine temps and get in to closed loop operation).

2) Drive with a steady vehicle speed between 40 & 60 mph for 2 minutes.

3) Idle vehicle for three (3) minutes.

Evaporative System Monitor Drive Trace

Trace 1: Standard Type

Pre-Conditioning Requirements:

- MIL must be off.

- No Evaporative DTCs present.

- Fuel level is between ½ and full.

(Note: monitor may still run with tank fill between 15% and 85%).

Driving Procedure

1) Idle vehicle for five minutes (to reach closed loop operation).

2) Drive with a steady vehicle speed between 30 and 45 mph for 2 minutes.

Trace 2: Leak Detection Pump

Pre-Conditioning Requirements:

- MIL must be off.

- No Evaporative DTCs present.

- Fuel level is between 30 & 85 % full.

Driving Procedure

1) Cold soak vehicle, start and idle vehicle for 4 minutes.

2) Drive in-town (stop and go) for 5 minutes, using smooth acceleration and deceleration.

3) Stop and idle vehicle for 4 minutes.

O2 Sensor Monitor Drive Trace

Pre-Conditioning Requirements:

- MIL must be off.

Driving Procedure

1) Idle vehicle for five minutes (to reach closed loop operation).

2) Drive with a steady vehicle speed above 25 mph for 2 minutes.

3) Stop and idle for 30 seconds.

4) Smoothly accelerate to a speed between 30 and 40 mph.

5) Repeat steps 3 & 4 five (5) times.

O2 Sensor Heater Monitor Drive Trace

Pre-Conditioning Requirements:

- MIL must be off.

Driving Procedure

1) Idle vehicle for five minutes (to reach closed loop operation).

2) Shut engine off and leave vehicle off for ten minutes.


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