MAP Posted October 3, 2012 Share Posted October 3, 2012 I have a stock gt with 102,600 mi and 5EAT. This past week the CEL has been turning on and off continuously, and i dont mean that its flashing. It sometimes turns on for a couple minutes then turns off. Sometimes it only turns on for a few seconds then turns off. The cruise light does not turn on. I have an auto xray scanner and it doesnt detect any codes or pending codes. I found this odd so i tried to make it set a code by disconnecting the MAP sensor. This caused the CEL to light and cruise light to flash and set a code. I changed the spark plugs thinking it may be a minor misfire that isnt obvious. I had to take the battery out to get to the driver side plugs. The CEL is still turning on. The engine runs fine. Any ideas? When i was trying to set a code, I tried leaving the gas cap off for a couple minutes and to my surprise this didnt set a code. In the past a loose gas cap caused a CEL and cruise light to flash. Im thinking maybe theres a vacuum leak. But if there were why wouldnt a code be set? Whats the point in the CEL turning on if a code isnt set? Any ideas would be appreciated. Thanks, MAP Link to comment Share on other sites More sharing options...
ehsnils Posted October 3, 2012 Share Posted October 3, 2012 This can be just about anything. But do you have the scanner connected at all times? Maybe you get noise on the CAN bus and that triggers the CEL. It can also be another ECU that's quirky. You may try to disconnect different fuses and change things to try to isolate the problem. If you drive with seatbelt on, try to not have it on, connect the passenger seat belt even though you don't have a passenger, remove ABS fuse etc. One thing at a time to see if the problem goes away. And also check that all fuses are OK and you don't have a bad electrical connection somewhere. Link to comment Share on other sites More sharing options...
MAP Posted October 6, 2012 Author Share Posted October 6, 2012 This is definitely going to be a pain to figure out. Thanks for the suggestion. Link to comment Share on other sites More sharing options...
shroom Posted October 8, 2012 Share Posted October 8, 2012 had a similar issue, took the gas cap and put it back on and it was gonzo Link to comment Share on other sites More sharing options...
MAP Posted October 8, 2012 Author Share Posted October 8, 2012 Wish it were that easy. Bought new gas cap about a year ago to prevent that problem.(i.e. probably worn seal on old cap). Ive already put gas in the car and tightened it several times past clicking... Still same issue. Link to comment Share on other sites More sharing options...
MAP Posted October 27, 2012 Author Share Posted October 27, 2012 The CEL has continued to turn on and off without settng a code. One odd thing that i have noticed is that when i go over harsh bumps, this sometimes causes the CEL to turn on. It has happened too many times to be a coincidence. Has anyone had a similar experience? It just blows me away that they would program the CEL to turn on without setting a code. Whats the point in that? Maybe the Subaru dealer equipment/scanner has the ability to identify the item causing the CEL to turn on. MAP Link to comment Share on other sites More sharing options...
06silvarubiLGT Posted October 27, 2012 Share Posted October 27, 2012 I think I read somewhere about someone having a problem like this. Ended up being a knock sensor picking up a clunking noise in front end somewhere.. Not sure if this is what you have going on but it sounds remotly similiar. dont think 05-06 have Can systems I could be wrong there tho Link to comment Share on other sites More sharing options...
Spec B Posted November 1, 2012 Share Posted November 1, 2012 Any solution found? Having very similar problem after changing my battery. http://legacygt.com/forums/showthread.php/fast-blinking-cel-cruise-light-not-195414.html Link to comment Share on other sites More sharing options...
MAP Posted November 2, 2012 Author Share Posted November 2, 2012 Nope. Still doing it but my CEL doesnt flash. It comes on and stays on for certain amount of time(could be few seconds, minutes)then turns off for a bit(again might be off for minutes or only seconds) then it turns on again. There is no pattern to this. The car runs fine, no codes set. Is your CEL constantly flashing when it does come on? Link to comment Share on other sites More sharing options...
Spec B Posted November 3, 2012 Share Posted November 3, 2012 Flashes slowly and then speeds up and flashes quickly. I think something is wrong with the ecu...when I turn the ignition, before starting it, the fans are cycling on and off(like it does when the green connectors are connected). Link to comment Share on other sites More sharing options...
MAP Posted November 9, 2012 Author Share Posted November 9, 2012 I took off my gas cap today for the drive home from work, 20 miles, and no code was set. The check engine light stayed on most of the time only turning off for a few seconds a couple of times. The cruise light did not flash. Can someone on here do me a favor and try taking off the gas cap and drive a bit to see if this sets a code?(i.e. causes CEL to turn on and cause cruise light to flash) Just please only do this if you have half a tank or less. I dont want anyones gas to start pouring out while making a left turn. If this sets a code right away then I think my problem may be related to the evaporative emission system. Thanks Link to comment Share on other sites More sharing options...
Max Capacity Posted November 9, 2012 Share Posted November 9, 2012 Have the code read at any auto parts store, they do it for free 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
MAP Posted November 9, 2012 Author Share Posted November 9, 2012 I have a scanner. The issue is no trouble code is being set, which makes troubleshooting this difficult. My guess is this is something only Subarus system would be able to detect. (I.e. not a generic OBDII issue) This is why Im asking for someone or several people to take the gas cap off. I want to detrrmine how long it would normally take for a CEL to come up. If it doesnt set a code then there's nothing unique about my situation. But if a code is set for someone else, or several people then I know theres something wrong with the evaporative emission system, since my ECU doesnt set a code. Link to comment Share on other sites More sharing options...
Max Capacity Posted November 9, 2012 Share Posted November 9, 2012 How old is the battery ? are the terminals clean and tight ? 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
MAP Posted November 10, 2012 Author Share Posted November 10, 2012 The battery is a year old. Terminals are tight. I usually replace a battery after 5 years whether I have a problem or not. They dont give much warning before they go. Link to comment Share on other sites More sharing options...
MAP Posted November 14, 2012 Author Share Posted November 14, 2012 Did anyone try taking off the gas cap? Link to comment Share on other sites More sharing options...
Max Capacity Posted November 14, 2012 Share Posted November 14, 2012 You may want to PM m sprank or BAC5.2 or Frank_ster one of them may be able to help you. I don't think anyone is going to want to drive without the gas cap on to see if the CEL comes on. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
MAP Posted November 14, 2012 Author Share Posted November 14, 2012 So no one is willing to take the gas cap off while the car is idling or drive around the block or a couple blocks to see if a code will be set? If these cars set a code from a loose gas cap, I wouldnt think it would take long to set a code if the cap were left off. Oh well... One of these coming weekends Ill check the vacuum hoses and connections near the tank. If I cant figure it out I'll take it to the dealer. Link to comment Share on other sites More sharing options...
MAP Posted February 10, 2013 Author Share Posted February 10, 2013 Well i finally ended up taking the car to the dealer. They said the tech was able to pull a p0038 code from freeze frame data. That code is for a high reading from the downstream oxygen sensor. They claimed they were getting erratic readings. They suggested replacing the oxygen sensor for $400. I didnt understand why i couldnt read a code. I told them i would install the sensor myself and thanked them for the diagnosis. Left with the car and again only the cel was turning on and off every so often. Went to Sams and when I turned on the car what does it do? Something it hadnt done in 6 months of the CEL turning on and off. It set a trouble code!! The CEL was lit solid and cruise control light was flashing. Checked the code with my scanner and just as they said... P0038. I have to believe that they updated software or enabled something such that it now was able to set a code. Anyway I ordered the denso oxygen sensor for $60 from rockauto and installed it in 15-20 minutes... What crooks the dealers are... Well i cleared the codes before removing the sensor. i turned the car on and the damn CEL comes on. Im a little disappointed as i had hoped it would be an easy fix. I had checked the heater resistance of both the new and old sensor and both measured about 6 ohms. I thought maybe the old one was opening up once it got warmed up. So i disconnect the sensor and get a p0037 code. So then I assume theres some kind of short in the wiring. I follow the wiring and dont find a problem all the way to the ecm. I open the ecm just for the hell of it and locate the transistor that grounds the o2 sensor heater. I checkmthe resistance across drain and source and get a reading of ~ 5 kohms. That transistor should have a resistance of high megohms or read open. So i figured I found the problem, order a replacement transistor and put the ecm back in since i need the car for the week. I also end up changing the battery since one of the cells was bad... Another story.. Didnt strap it properly a while back it hit the sheet metal created an acid leak etc... Anyway i put the new battery on and theres no trouble code. Drove it all week and no trouble code. Checked the resistance of the transistor by disconnecting the connector of the 02 harness at the top of the transmission and it still reads 5kohms. Why the ecm isnt setting a code imdont know. But i was able to g et the car smogged tested with no issue, so i wont worry about it until the CEL comes on Again. Link to comment Share on other sites More sharing options...
ehsnils Posted February 10, 2013 Share Posted February 10, 2013 5 kOhm is essentially same as open circuit and in some cases the ECU has some diagnostic circuits added to check the circuits and that can cause the 5kOhm reading. What you should do is to measure the voltage on that circuit with engine off, on and so on to see if it behaves correctly. Link to comment Share on other sites More sharing options...
MAP Posted February 10, 2013 Author Share Posted February 10, 2013 Thinking about it youre right. Via the 5k resistance between drain and source they are checking that the transistor is turning on and off when its commanded to. When on the resistor is bipassed and all current flows through the transistor. When off there should be a small voltage drop across the resistor. Since my check engine was coming on and off intermittently and sometimes when i was going over bumps, the oxygen sensor heater circuit must have had an intermittent open. Thanks for that input. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.