danielzink Posted May 30, 2020 Share Posted May 30, 2020 Starting this winter the wife's car (99 Forester) when starting in the morning would run like it had a fouled plug. After about a minute it would "clean out" and run fine. CEL has been on since then. I had "assumed" it was a bad O2 sensor(s). I ran my Torque app this morning and pulled these fault codes: B0303 - Body B0304 - Body C0000 - Chassis C0304 - Chassis C0340 - Chassis P0304 - Powertrain Cylinder 4 misfire detected P0404 - Powertrain EGR control circuit range/performance P0420 - Powertrain Catalyst system efficiency below threshold (bank 1) P0440 - Powertrain Evaporative emission control system P0483 - Powertrain Cooling fan rationality check P2043 - Powertrain Reductant temperature sensor circuit range/performance Also - upon further inspection it looks like the car only has (1) O2 sensor ? Or am I not looking in the right spot for the second one ? Any advice is welcome ! Thanks ! Dan Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted May 30, 2020 Share Posted May 30, 2020 (edited) O2 sensors don't work when cold. If the problem is on first start and gets better as the O2's come online then that's not your issue. You have a lot of codes. You should probably start with a tune up (plugs and wires), clean the MAF (scrape the elements with a pick and use brake cleaner), and then clear the codes and test drive. Watch fuel trims, and see what codes return. Cylinder 4 misfire... if it doesn't resolve with a tune up you should do a valve adjustment asap as you may have a tight exhaust valve on #4 which will not end well if allowed to progress. GD Edited May 30, 2020 by GeneralDisorder 1 Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted May 31, 2020 Share Posted May 31, 2020 clear the codes and see which ones return first. could have a bad seal on the gas cap or rusted-thru holes on the filler tube causing the 440. next time it's cold, you could pull plugs and see if one is wet with fuel - maybe an injector is leaking into the cylinder. Quote Link to comment Share on other sites More sharing options...
danielzink Posted June 2, 2020 Author Share Posted June 2, 2020 On 5/30/2020 at 12:00 PM, GeneralDisorder said: O2 sensors don't work when cold. If the problem is on first start and gets better as the O2's come online then that's not your issue. You have a lot of codes. You should probably start with a tune up (plugs and wires), clean the MAF (scrape the elements with a pick and use brake cleaner), and then clear the codes and test drive. Watch fuel trims, and see what codes return. Cylinder 4 misfire... if it doesn't resolve with a tune up you should do a valve adjustment asap as you may have a tight exhaust valve on #4 which will not end well if allowed to progress. GD I cleared all the codes via the Torque app. At this point (approx 100 miles) no more codes have appeared. I'm going to order new wires from RockAuto and plugs and do those when they arrive. I also bought some MAF spray cleaner from the local FLAPS. Thanks, Dan Quote Link to comment Share on other sites More sharing options...
danielzink Posted June 2, 2020 Author Share Posted June 2, 2020 On 5/31/2020 at 2:53 PM, 1 Lucky Texan said: clear the codes and see which ones return first. could have a bad seal on the gas cap or rusted-thru holes on the filler tube causing the 440. next time it's cold, you could pull plugs and see if one is wet with fuel - maybe an injector is leaking into the cylinder. See above post - codes have been cleared. To address your point - I replaced the entire filler tube 2 years ago as *yes* it was completely rusted through. I purchased and installed a new gas cap at the same time as filler tube replacement. Thanks, Dan Quote Link to comment Share on other sites More sharing options...
danielzink Posted June 2, 2020 Author Share Posted June 2, 2020 I suppose I'm also confused as to the lack of a second O2 sensor ? Any input ? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 2, 2020 Share Posted June 2, 2020 (edited) 41 minutes ago, danielzink said: I suppose I'm also confused as to the lack of a second O2 sensor ? Any input ? It's there. Look harder. The "MAF cleaner" is pretty useless. It's watered down brake cleaner. Just use full strength brake clean and you MUST scrape the elements with a pick. Otherwise you may as well just buy a new one. GD Edited June 2, 2020 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
Numbchux Posted June 2, 2020 Share Posted June 2, 2020 Is that a bung welded shut after the cat? Yea, you should have an upstream and downstream. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 2, 2020 Share Posted June 2, 2020 You are both looking AT a bung. You should be looking FOR a sensor. Trust me it's there. GD Quote Link to comment Share on other sites More sharing options...
el_freddo Posted June 2, 2020 Share Posted June 2, 2020 5 hours ago, GeneralDisorder said: You are both looking AT a bung. You should be looking FOR a sensor. Trust me it's there. GD I see one sensor on the lower end of the car in the pic - so where is the SECOND sensor that they’re trying to find? I too can only see a bung for a second sensor. I’m not 100% sure that it’s got a second O2 sensor, but I’m not overly familiar with the forester. Cheers Bennie Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 2, 2020 Share Posted June 2, 2020 (edited) You are looking at 14" of the 10' long exhaust system..... trust me it's there. The scan data tells everything you need to know. First there is a complete absence of ANY codes related to the secondary sensor circuit - which would be present immediately if it were unplugged. Second, there ARE codes related to converter efficiency - which could only be generated by a secondary sensor that is sending data for the ECU to compare to primary sensor data. The fact that it has a P0420 code tells us it's there. All 95+ Subaru's have secondary sensors in the US. It was mandated by law. And if the OP can't get down there with a flashlight and find the sensor, or google image it's whereabouts on his model.... well I don't have the time to type out it's exact location. GD Edited June 2, 2020 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
heartless Posted June 2, 2020 Share Posted June 2, 2020 Never "assume" things.. you know what they say about that... i would suggest you start by downloading the factory service manual for the vehicle http://jdmfsm.info/Auto/Japan/Subaru/ there are in fact two O2 sensors, one up close to the engine just after the junction of the manifolds (Y pipe), and the other is well behind the wheel well area - roughly in the vicinity of the gear selector (i know because I need to replace that one on my 2002 Foz) at the end of a secondary cat/resonator.. not sure what that is a picture of, but it does not look right (ie: correct) to me. Quote Link to comment Share on other sites More sharing options...
andrsn Posted June 30, 2020 Share Posted June 30, 2020 Sorry to go off topic but do earlier ej22's (1991-obd1) have 1 o2 sensor or 2? Quote Link to comment Share on other sites More sharing options...
el_freddo Posted July 1, 2020 Share Posted July 1, 2020 @andrsn Gen1 and Gen2 have only one O2 sensor. It’s located between the two exhaust pipes coming into the cat converter. Cheers Bennie 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.