P1138 code on my 97 4.0SE
#1
01-22-2013, 10:35 PM
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P1138 code on my 97 4.0SE
CEL just lit up and my obd2 scanner showed this code. From recent searches, I'm finding that my truck is running rich? Can someone please confirm this and/or advise me what my next move should be to troubleshoot this problem? MAF cleaning? Fuel injector replacement? Any advice is greatly appreciated.
#2
01-23-2013, 12:23 AM
Super Moderator
From the GEMS ECU manual some notes:
Response Rate Measurements
The response rates of the controlling oxygen sensors are measured. This measurement will take place during the normal sensor switching, which occurs in closed loop control. If either of the response times in the Lean to Rich direction or the Rich to Lean direction are greater than their respective maximum limits, then the appropriate response rate fault counter will be incremented; the counters will be decrement to zero if the appropriate response time is less than its limit. If either counter reaches its maximum value then the appropriate response rate fault is present. The fault will remain present until the counter reaches zero.
The response rates of the controlling oxygen sensors are measured. This measurement will take place during the normal sensor switching, which occurs in closed loop control. If either of the response times in the Lean to Rich direction or the Rich to Lean direction are greater than their respective maximum limits, then the appropriate response rate fault counter will be incremented; the counters will be decrement to zero if the appropriate response time is less than its limit. If either counter reaches its maximum value then the appropriate response rate fault is present. The fault will remain present until the counter reaches zero.
A page from the manual is attached that shows how that code is enabled. The MAF is part of it, so cleaning MAF, when stone cold, with made-for-MAF spray may help. Misfires and O2 sensors can also be an issue. The computer is always trying to test the O2 sensors to be sure they are awake.
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philander
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