- Jun 11, 2003
Here goes....The girlfriend's '99 4unner 3.4 liter 4runner with 5 speed manual tranny is having some issues. She purchased 2 years ago from an area Toyota dealer with 35,000 miles and it now has about 72K. Couple of days ago the check engine light came on with 2 codes (P0125 and P1135). Oil level seemed a hair low but nothing crazy and was recently changed with a filter and Mobil 1 5w 30. I reset the ECU and disconnected the battery overnoght but the codes retruned within 5 minutes of driving the next day. In searching for information on these codes I have become a bit concerned. It seems as if it may need an 02 sensor but some have said that the o2 sensors are treating a symptom and not the problem which may be Engine Sludge! Toyota seems to have had a problem with some engines (mostly 3.0 liter) and sludge and they replace the engines, but I have heard of 3.4s having the same issues. However, this certified pre-owned truck is now out of warranty and since I change the oil myself, I have no receipts of maintenance. I am planning to test the voltage across the o2 sensors as someone suggested but in the event the sensors are ok, I am not sure how to proceed. I've looked on Yotatech but have never had any sort of quality tech response from that site and after three hours researching this issue I am at a loss. Anyone have any advice about how I should proceed. I have been very unhappy with our local Toyota dealer in the past and have since completed all the work on my 80, my sister's 4unner, parent's 100, and girlfreind's 4runner myself. I do not really trust them to examine/diagnose this problem but if I do have to take it there I want to know everything about the problem beforehand so that if the engine needs replacement we are not out $5000. Please help....anything technically related or advice is greatly appreciated.