98 OBDII Codes- Help
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98 OBDII Codes- Help
I have a check engine light on giving me a OBDII manufacturer code of 1506 and a general code of 0171(system to lean Bank 1) and 0174 (system to lean Bank 2). What do these codes mean? I have been told it could be an O2 sensor. What could be the problem?
Thanks
Grillian
Thanks
Grillian
Senior Member
Joined: Aug 2002
Posts: 357
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From: Winchester, MA
Others know more about these codes than I do, but I'll bump you to the top of the list and also give you my take.
Before you replace the O2 sensors, try cleaning you MAF sesnor in the air cleaner housing. If it gets dirty it can trip the CEL and cause a lean situation. After resetting the computer, check to see if the CEL comes back on. If it does, check for vacuum leaks. There are a couple of years that seem to be prone to vacuum lines/fittings cracking a causing a lean situation.
Now the O2 sensors may be the culprit, but if I were you, I'd check the easy stuff first.
Before you replace the O2 sensors, try cleaning you MAF sesnor in the air cleaner housing. If it gets dirty it can trip the CEL and cause a lean situation. After resetting the computer, check to see if the CEL comes back on. If it does, check for vacuum leaks. There are a couple of years that seem to be prone to vacuum lines/fittings cracking a causing a lean situation.
Now the O2 sensors may be the culprit, but if I were you, I'd check the easy stuff first.
Senior Member
Joined: Sep 2000
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From: Mpls, MN
Sheesh
I wish I could get a code like this. Our Explorer runs like ****; as though there is a major vacuum leak, but will not throw a code and I can't find anything odd
It's not the HO2 sensors. They are doing their job and letting you know that more air is getting into the engine than the MAF is measuring. Basically, you're running lean.
Clean the MAF, yes. Also check for loose hose connections on the intake manifold and air intake tube.
I wish I could get a code like this. Our Explorer runs like ****; as though there is a major vacuum leak, but will not throw a code and I can't find anything oddIt's not the HO2 sensors. They are doing their job and letting you know that more air is getting into the engine than the MAF is measuring. Basically, you're running lean.
Clean the MAF, yes. Also check for loose hose connections on the intake manifold and air intake tube.
Technical Article Contributor
Joined: Jun 2002
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From: Under the flightpath of old ORD 22R
The other place that un-metered air gets into the system could be the rubber elbow on the back of the throttle body for the PCV.
Have you put a FIPK or changed the air filter as of late. This is where a loose hose connection that AJ mentioned might have come from. Changing the air filter can cause one of these hoses to come loose, without you meaning to do it.
The step by step problem diagnoses that some members posted back can be seen by doing a search on P0171 if you want to see them.
As for the 3rd code P1506 from teh manual :
DTC
P1506 - Idle Air Control (IAC) Overspeed Error
Description
This DTC is set when the PCM detects engine idle speed that is greater than the desired rpm.
Possible Causes
IAC circuit short to GND
Damaged IAC valve
IAC valve stuck open
Vacuum leaks
Failed EVAP system
Damaged PCM
Diagnostic Aides
Disconnect IAC valve and look for little or no change in engine rpm as an indication of a stuck or damaged valve.
When you are checking the rubber PCV elbow on the back of the throttle body, you will see a cylinder ( kind of like a coil from a motor cycle, but not black in color ) that is the IAC.
I would take this 3rd code to mean that the cause of the lean condition is a vac leak, mroe then a dirty MAFS ( can't hurt to clean it anyway ) so maybe finding the source of the P1071 and P0174 DTC first, make the repair and reset the PCM, to see if the P1506 is actually a seperate issue might be in order.
You can try to unplug the IAC and see if the truck stumbles at idle, if you want, but I would take a SWAG and say the vac leak might be in the correct place to cause the un-metered air to get into the system, as well as maybe causeing the IAC not to close.??
Sorry I have never gotten this myself, so I can't say for sure if this is the case. Good luck, and post back what you found for the next member, or if you are having problems finding stuff.
Good luck.
Steve
Have you put a FIPK or changed the air filter as of late. This is where a loose hose connection that AJ mentioned might have come from. Changing the air filter can cause one of these hoses to come loose, without you meaning to do it.
The step by step problem diagnoses that some members posted back can be seen by doing a search on P0171 if you want to see them.
As for the 3rd code P1506 from teh manual :
DTC
P1506 - Idle Air Control (IAC) Overspeed Error
Description
This DTC is set when the PCM detects engine idle speed that is greater than the desired rpm.
Possible Causes
IAC circuit short to GND
Damaged IAC valve
IAC valve stuck open
Vacuum leaks
Failed EVAP system
Damaged PCM
Diagnostic Aides
Disconnect IAC valve and look for little or no change in engine rpm as an indication of a stuck or damaged valve.
When you are checking the rubber PCV elbow on the back of the throttle body, you will see a cylinder ( kind of like a coil from a motor cycle, but not black in color ) that is the IAC.
I would take this 3rd code to mean that the cause of the lean condition is a vac leak, mroe then a dirty MAFS ( can't hurt to clean it anyway ) so maybe finding the source of the P1071 and P0174 DTC first, make the repair and reset the PCM, to see if the P1506 is actually a seperate issue might be in order.
You can try to unplug the IAC and see if the truck stumbles at idle, if you want, but I would take a SWAG and say the vac leak might be in the correct place to cause the un-metered air to get into the system, as well as maybe causeing the IAC not to close.??
Sorry I have never gotten this myself, so I can't say for sure if this is the case. Good luck, and post back what you found for the next member, or if you are having problems finding stuff.
Good luck.
Steve
