Subaru WRX Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
Hey guys, hoping I can get some ideas on how to address this issue.

2015 WRX Base, no mods, 23.5k miles.

I currently have a check engine code P0030 on the car, which is the third time I've had this code in the last 2 months. The first time this code appeared the heated O2 sensor was replaced by the dealer under warranty. I was able to drive the car with no issues at all for about 3 weeks. After a rainy day, I drove the car and the CEL came on again reporting the same P0030 code. I wasn't able to get the car into the dealer since it was the end of the weekend, but when I went to take the car in again the CEL turned off reporting no issues. The dealer tested the O2 sensor again and decided to replace it. Again, no issues for around 3 weeks and this past weekend, after a very rainy day, the CEL came back on again with the P0030 code.

From some of the research I've done I see that this is a part that shouldn't need to be replaced that often. One source indicated that this is considered a "lifetime" part and shouldn't even need to be checked until around 100k miles.

My question, am I just getting a bunch of bad O2 sensors, or could there be another issue that is causing the sensor to fail?

If I remember correctly from some of the videos I've watched on the replacement of this sensor on other Subarus, the sensor and wiring harness are under the car right before the catalytic converter. Is it possible that water is getting into the sensor/wiring harness causing a short that breaks the sensor? The reason I ask is because the CEL appears after the car is driven on a rainy day.
 

·
Registered
Joined
·
44 Posts
Was the weather dry when the CEL turned off? If so it would indicate that there is a way for water to get into the wiring and then dry out. As this has happened with two different sensors there is a good chance that the problem is in the wiring harness. If you can look at the connector, see if the seal on the front side is intact and the seals on the individual wires into the connector on the back are not damaged.
Good Luck
 

·
Super Moderator
Joined
·
11,451 Posts
That's an odd one. If it's repeating I would suspect a bad connection or ground in the harness. Possibly a relay or fuse, bad connector on the harness itself, or contamination of a ground elsewhere.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #4 ·
Was the weather dry when the CEL turned off? If so it would indicate that there is a way for water to get into the wiring and then dry out. As this has happened with two different sensors there is a good chance that the problem is in the wiring harness. If you can look at the connector, see if the seal on the front side is intact and the seals on the individual wires into the connector on the back are not damaged.
Good Luck
Yeah, the CEL turned off when the weather was dry. The car was also parked in my garage over the weekend until I could get it into the dealer.

However, today was a nice day as well but the CEL didn't reset. I'll have to see if I can get under the car to inspect the wiring harness.
 

·
Water.....sometimes waves
Joined
·
1,612 Posts
I HAVE THIS EXACT (almost) ISSUE!

But I get the P0420 code. My CEL comes on it seems mostly when raining, but sometimes not. Sometimes it will turn off on the very next startup and sometimes it will go a couple weeks before turning off. I had come to the conclusion originally that it was moisture in my connector. But lately I am not so sure. I still plan to check the moisture theory as soon as the weather warms up here and I can comfortably get under there. I plan to disconnect and put dielectric grease on things inside the connector then connect it. The grease should keep moisture out and eliminate that as a cause.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #6 ·
The dealer checked the HO2 sensor and discovered that it is working fine. They determined there was a service bulletin for the ECU. They updated the ECU, so let's see if that code stays away now.
 

·
Water.....sometimes waves
Joined
·
1,612 Posts
Thanks for posting this. Please post again in a while and update if it indeed solved your problem.

I just drove to an from work yesterday in one of the biggest rain/slush storms of the season and my light did NOT come on. This sort of poo-poos the moisture theory. If yours stays off, I may have to take mine in and mention the ECU update.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #8 ·
It's been just over a week with no issues. I've put about 200 miles on the car during that time without any new CEL. I'll try to remember to post again at the end of the month.
 
1 - 9 of 9 Posts
Top