Jeep Cherokee Evap "very small leak" code P0456 fixed, but sensor not ready

[LeeH]

2014 Cherokee V6 was throwing a P0456 code. If cleared, it took a week or so to return. I replaced sensors at either end of the evap system. I haven't seen a code in a couple of months, but when plugged in to the reader, the evap still shows "not ready." I've driven a few thousand miles with no CEL, but still have a yellow light on the reader and the evap symbol flashing. What can I do the clear this? Fortunately, AZ emissions passed it since only one system was not ready and the CEL was off, but I'd really prefer to know it's truly resolved. Any suggestoins?

[Bob Kontak]

Not a fan of evap monitors. However there is some logic.

Maybe you can only do the evap monitor part.

Cold start and follow guidance as closely as possible. Put your tank at 3/4 full.

Jeep Cherokee Drive Cycle

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.

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 30 & 45 mph for 2 minutes.

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.

[LeeH]

I guess it's possible that even in a couple of thousand miles of driving that I haven't exactly met those parameters... especially the idle for 5 minutes before shutoff. I've got an oil change coming up and will have it at the dealer. Will see if I can get an audience with a tech. Yes... I get oil changes at the Jeep dealer. They're 3 for $100 and since I have an extended warranty, I want record they were done. Plus... when they come back and say, "Oh... this is broken," I just remind them about the warranty and the "this" gets fixed!

[GH85Carrera]

Originally Posted by Bob Kontak

Not a fan of evap monitors. However there is some logic.

Maybe you can only do the evap monitor part.

Cold start and follow guidance as closely as possible. Put your tank at 3/4 full.

Jeep Cherokee Drive Cycle

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.

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 30 & 45 mph for 2 minutes.

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.

WOW! Golly modern cars are great.

That is astonishing. All that to clear a code about air conditioning. I guess in many parts of Arizona, AC is vital. I had no idea the AC system was monitored like that on modern cars.

It makes me think of my 85 911. It did not even come with a pressure cutoff switch, so the refrigerant could leak out, and the compressor keep running unit it destroyed itself. Cars have come a long way since the 80s.

[Bob Kontak]

Originally Posted by GH85Carrera

WOW! Golly modern cars are great.

That is astonishing. All that to clear a code about air conditioning. I guess in many parts of Arizona, AC is vital. I had no idea the AC system was monitored like that on modern cars.

Evap codes are not air conditioning even though it sounds like it from terminology.

It's a system that has been on all cars for decades but given what you fiddle with Glen, you probably don't see this stuff since they are post 1994-ish with OBD2.

Evap means evaporative emissions. When you or others fill a car or lawnmower gas tank you have seen the vapor coming out around the filler neck. That's evaporative emissions.

The EPA requires a car to self test it's ability to not leak gas tank vapors. I'm not sure when testing if it pulls a vacuum or pressurizes the vapor venting and recovery system but the car has to hold the pressure or the vacuum for a certain length of time or it throws a code. If it leaks fast it throws one code. If it leaks slow it throws another.

Often it's the just gas cap seal.

That said, OP's car won't run the self test in timely manner. Driving cycle may hasten the self test.

[GH85Carrera]

Yep, shows what I know.

[Bob Kontak]

Originally Posted by GH85Carrera

Yep, shows what I know.

You know plenty.

Your 3.2 has the system but it does not have the self test as it was not EPA required.