Check Engine Light
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Member
Joined: Oct 2011
Posts: 192
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From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
Check Engine Light
Hi, just bought my first Jeep yesterday. I was actually very impressed with the 4.0. Kind of suprised me.
I drove it home, "an hour away", and ran perfect! But the check engine light is on. The owner told me he thought it came on when he unplugged the a/c. But he wasn't sure. Is there a way for me to check the codes at home?
I don't even know if there is a code chart online. It does run very nice, thats why I am confsued.
1998 Jeep 4.0 Auto.
I drove it home, "an hour away", and ran perfect! But the check engine light is on. The owner told me he thought it came on when he unplugged the a/c. But he wasn't sure. Is there a way for me to check the codes at home?
I don't even know if there is a code chart online. It does run very nice, thats why I am confsued.
1998 Jeep 4.0 Auto.
Thread Starter
Member
Joined: Oct 2011
Posts: 192
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From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
Oh, I didn't know Advance could do that with the Jeeps.
I can't believe I have a code, and it runs so nice. Kind of confusing! I will do all the oil change, anti freeze change...etc. And have them check it.
I can't believe I have a code, and it runs so nice. Kind of confusing! I will do all the oil change, anti freeze change...etc. And have them check it.
CF Veteran
Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
On a 98, codes must be read with either a code reader or a scan tool. As mentioned, Autozone and others can read this code for you for free.
But be SURE to get the exact code number and post it here. Interpreting codes is not always straight forward and with codes, the devil is in the details!
But be SURE to get the exact code number and post it here. Interpreting codes is not always straight forward and with codes, the devil is in the details!
Thread Starter
Member
Joined: Oct 2011
Posts: 192
Likes: 0
From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
On a 98, codes must be read with either a code reader or a scan tool. As mentioned, Autozone and others can read this code for you for free.
But be SURE to get the exact code number and post it here. Interpreting codes is not always straight forward and with codes, the devil is in the details!
But be SURE to get the exact code number and post it here. Interpreting codes is not always straight forward and with codes, the devil is in the details!
Thread Starter
Member
Joined: Oct 2011
Posts: 192
Likes: 0
From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
Okay the code was:
P0443
Evaporator Seloid Valve
Advance said they didn't have one, and had no idea where it was on the vehicle? That was the only code that showed up.
Any ides where this is located at? Ran very smooth still, but I need emissions done, and they will fail it. Thanks very much.,
P0443
Evaporator Seloid Valve
Advance said they didn't have one, and had no idea where it was on the vehicle? That was the only code that showed up.
Any ides where this is located at? Ran very smooth still, but I need emissions done, and they will fail it. Thanks very much.,
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Thread Starter
Member
Joined: Oct 2011
Posts: 192
Likes: 0
From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
CF Veteran
Joined: May 2009
Posts: 10,423
Likes: 61
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
P0443: Jeep: Evaporative Emission System Purge Control Valve Circuit
Check your gas cap, make sure its on good. Drive for a while, see if it goes out. if not youll have to do some more investigating.
Check your gas cap, make sure its on good. Drive for a while, see if it goes out. if not youll have to do some more investigating.
CF Veteran
Joined: May 2008
Posts: 2,202
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From: Brighton, MI
Model: Cherokee
If they didn't clear the code when they read it, disconnect the battery and see if it comes back on.
CF Veteran
Joined: May 2009
Posts: 10,423
Likes: 61
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Really?
Once a Type A or B code has been set, the MIL will come on and remain on until the component that failed passes a self-test on three consecutive trips. And if the fault involved something like a P0300 random misfire or a fuel balance problem, the light will not go out until the system passes a self-test under similar operating conditions (within 375 rpm and 10% of load) that originally caused it to fail. That is why the MIL lamp will not go out until the emissions problem has been repaired. Clearing the codes with a scan tool or disconnecting the powertrain control module power supply will not prevent the lamp from coming back on if the problem has not been fixed. It may take one or more driving cycles to reset the code, but sooner or later the MIL lamp will go back on if the problem is still there.
Suppose you have "fixed" an emissions problem on an OBDII-equipped vehicle. How can you check your work? By performing what is called an "OBDII drive cycle."
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
Last edited by 89Laredo; Oct 17, 2011 at 12:04 PM.
CF Veteran
Joined: May 2008
Posts: 2,202
Likes: 0
From: Brighton, MI
Model: Cherokee
Really?
Once a Type A or B code has been set, the MIL will come on and remain on until the component that failed passes a self-test on three consecutive trips. And if the fault involved something like a P0300 random misfire or a fuel balance problem, the light will not go out until the system passes a self-test under similar operating conditions (within 375 rpm and 10% of load) that originally caused it to fail. That is why the MIL lamp will not go out until the emissions problem has been repaired. Clearing the codes with a scan tool or disconnecting the powertrain control module power supply will not prevent the lamp from coming back on if the problem has not been fixed. It may take one or more driving cycles to reset the code, but sooner or later the MIL lamp will go back on if the problem is still there.
Suppose you have "fixed" an emissions problem on an OBDII-equipped vehicle. How can you check your work? By performing what is called an "OBDII drive cycle."
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you have erased any trouble codes from the PCM memory, or after the battery has been disconnected. Running through the drive cycle sets all the system monitors so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
EDIT: Have had the CEL come on in both my XJ and my truck for my gas cap. Light didn't go off just by fixing it (tightening cap).
Last edited by OnlyInMyXJ22; Oct 17, 2011 at 12:36 PM.
Thread Starter
Member
Joined: Oct 2011
Posts: 192
Likes: 0
From: Maryland
Year: 1997
Model: Cherokee
Engine: 4.0
Okay, I did check the gas cap. It is tight. I disconnected the battery while I was working on some maint. stuff.
Light is still on.
The part that advance told me about, do I just need to change that part? I don't even know where it is. I am lost with this.
I have to replace my muffler and tailpipe, and maybe the cat. I can hear the cat making a "rattling noise" inside. Like the guts are loose. If that made any sense.
At idle, it is slightly rough, but nothing to really even focus on. I changed the plugs. Soon as you hit the throttle, it smooths out, and runs great. I am just trying to give as much info as possible. Sorry to be a pain.
The original owner told me that when he disconnected the a/c plug, "not sure why", he said he noticed the light after that. I dunno.
Light is still on.
The part that advance told me about, do I just need to change that part? I don't even know where it is. I am lost with this.
I have to replace my muffler and tailpipe, and maybe the cat. I can hear the cat making a "rattling noise" inside. Like the guts are loose. If that made any sense.
At idle, it is slightly rough, but nothing to really even focus on. I changed the plugs. Soon as you hit the throttle, it smooths out, and runs great. I am just trying to give as much info as possible. Sorry to be a pain.
The original owner told me that when he disconnected the a/c plug, "not sure why", he said he noticed the light after that. I dunno.