98 S70 Check Engine Light

New Guest · Post by **New Guest** » 31 Aug 2005, 10:39

Just found this site by accident and it has a lot of very good posts. I have a 98 S70 with 48,ooo miles that has been good up until recently. I had the front o2 sensor go out. Had that replaced and all was well. About a month later the "Check Engine" light came on and my local shop could not diagnose the problem. I have taken it twice to a Volvo dealer and after three hours of testing, they cannot locate the problem. Not the gas cap, not the 02 sensors, not any circut boards, etc. Everything is in range that they test. They clear the code and a day later the "Check Engine" light comes on again. At $75 per hour this is beginning to add up. Is there any way to clear the code at home without taking it to the dealer? Any other suggestions? I'm getting really frustrated.

Jot · Post by **Jot** » 31 Aug 2005, 13:53

An OBD2 code reader will clear the codes or disconnect the battery for couple of minutes.

Post by **matthew1** » 31 Aug 2005, 14:30

New Guest wrote: I have taken it twice to a Volvo dealer and after three hours of testing, they cannot locate the problem.

What codes did they pull? If you don't know, call them and get back to us.

guest · Post by **guest** » 31 Aug 2005, 17:50

Some auto parts stores will lend you an OBD2 scanner that you can use to pull the codes and then reset the light. In the Seattle area Schuck's auto will do it for you. In your 98 s70 the port is in the center console.

It is important to note down the codes that you pull. This will give you some insight into the source of the problem.

I am surprised your volvo dealer couldnt diagnose the problem. I dont think they should be charging you every time if it is a recurring problem...

Guest · Post by **Guest** » 31 Aug 2005, 18:53

The first code was a PO130. Replaced the front O2 sensor. The next code was PO107 (Baro Sensor). Reset the code. Then: Code EFI 422. Baro sensor signal. Removed panels and cowls, ECM and sensors for testing. Performed wiring and sensor tests. All wiring between the ECM and Barosensor/accel sensor/tank sensor (pressure) and a/c sensors passed tests. Could not find any shorts or grounds. All mentioned sensors would cause EFI 422.

After all that, the check engine light comes on again after two days. Any suggestions?