89 240 o2 sensor recommendations/suggestions.

BrickLover

(xpost from the volvo forum)

I have owned my 240 for almost 5 years, and as long as I've driven it people have said it runs rich. Most non-car people would just say something weird like "oh I love the smell of gasoline", so it has been fairly noticeable. The idles are a bit weird as well, often dropping and fluctuating, and sometimes I get various codes related to lamda/fuel mixture.

The current sensor is made by Denso (a local company), and was spliced in by Clayton Volvo of Knoxville in 2006. Over the years the wires have broken a couple times and I've spliced them back together to stop the "check engine" light from popping up, but this time I think the sensor has just been dead and not tripping the check engine light. When I remove the sensor connectors the engine runs the same, and seems to even run somewhat better. No check engine light or anything besides the normal condensation from the tailpipe and gas smell.

What sensors do you all recommend/have the best luck with? I see a large amount of sensors online but am not sure what would be best. As a student I try to save some money but understand the need for quality parts. Here are a couple I have been looking at:

https://www.ebay.com/itm/14330364163...m=143303641631

https://www.ebay.com/itm/15360926406...m=153609264062

https://www.ebay.com/itm/12195529623...m=121955296237

https://www.ebay.com/itm/38314203496...m=383142034965

Any links to guide on replacement would be great as well. It seems to be pretty simple but it's always nice to have instructions just in case. I can't really find a whole lot on this job so I guess it's simple.

Major Ledfoot

Your ebay links don't work.

I'd go with a quality Bosch sensor from FCP. Bosch is OE. It just plugs in.

https://www.fcpeuro.com/products/volvo-oxygen-sensor-front-240-740-244-245-940-780-760-bosch-13034

BrickLover

Major Ledfoot
Your ebay links don't work.
I'd go with a quality Bosch sensor from FCP. Bosch is OE. It just plugs in.
https://www.fcpeuro.com/products/volvo-oxygen-sensor-front-240-740-244-245-940-780-760-bosch-13034

Thanks for the advice! I'll go with the bosch but will have to shop around for a lower priced one just to see if that's possible. I found the same one on ebay for $89 so that's likely as low as they'll go.

GingerNinja

Second the Bosch 4.9 or whatever the latest version is. Plugs straight in although the cable was a bit long.

carnut222

If it’s running rich it could also be related to the ECU coolant temp sensor as they’re known to fail. Might be worth checking and if you’re ordering an O2 sensor order the coolant temp sensor as well to save on postage.

BrickLover

carnut222
If it’s running rich it could also be related to the ECU coolant temp sensor as they’re known to fail. Might be worth checking and if you’re ordering an O2 sensor order the coolant temp sensor as well to save on postage.

I replaced that with a new Bosch sensor when trying to fix the issue with running rich. Nothing changed, but the old sensor did have a big buildup on it. I was tempted to run it through my ultrasonic cleaner to see how it cleaned up, but never got around to it (transducer fried).

It was pointed out to me that my wagon has a head gasket leak it seems. A little white line runs down the side coming from the gasket, and has been for years. I just didn't know... Anyways people asked various questions so I did a 20 mile test drive without the o2 sensor plugged in. The car never ran that smooth before, but felt like it maybe had less power. It was running more lean judging by the lack of fuel smell.

The old sensor will be removed tomorrow if the shop can make a slot, and the new sensor will be here in a few days. But after that we aren't sure what to do about that head gasket issue. More people have said to just leave it alone since it isn't showing any head symptoms. No overheating, mix of fluids, etc. Someone pointed out the leak years ago but he was a very unpleasant fellow I thought was trying to take advantage, but maybe not. Myself and another volvo fan (who did this job on a 242) plan to do the head, but there's still debate on it and if we should risk it, or leave it until actual symptoms show up. I'd hate to do something to make the car worse.

carnut222

I assume you’ve checked the fuel pressure and fuel pressure regulator (to make sure no fuel is coming out the vacuum hose for the pressure regulator)?

PaddlerEd

The comment re the coolant temp sensor has got me thinking about our "new" Land Cruiser and it's inability to not run rich even with a new O2 sensor.

Quick dig around, and it looks like I might be up for $46 to get a new coolant sensor - but I might have one spare from the old 4Runner that would work, I just need to check the spare engine first... Unfortunately, the location on the 80 is on the side of the block and so necessitates draining the coolant, so all of a sudden it becomes a $100 job...

carnut222

I wouldn’t think a faulty O2 sensor would cause the car to run super-rich. The computer should detect a lack of signal fluctuation and throw the lambda (check-engine) light...and go for a default air-fuel ratio. On an LH2.4 car, assuming the O2 sensor is working properly, even if the temp sensor is bad, it should go into feedback mode once the O2 sensor and engine is warmed up so I don’t think it would run super rich unless it’s not in feedback mode. The computer will try to compensate (within reason) to maintain a stoichiometric fuel ratio IF the O2 sensor is working. If the fuel pressure is way too high, it won’t be able to compensate, and if the O2 sensor is bad it will run super-rich all the time. If you smell fuel but there’s no black smoke coming out the exhaust, I’d be looking for fuel leaks...or maybe the inlet manifold gasket is leaking and you’re getting raw fuel dripping out below the gasket?