[Hank]

I started running E30 fuel late last year to boost the performance of my RS for autox duty. Amazing performance for such little annoyance of blending fuel every 2-3 weeks. Now I'm starting to have persistent O2 sensor heater codes pop up on the Cobb AP and cause a CEL. I do have a catless downpipe and a j-pipe restrictor. Currently at 6,142 miles.

Current codes:
P0030 - Faulty Heated Oxygen Sensor HO2S (Bank 1 Sensor 1)
P0054 - Faulty Heated Oxygen Sensor HO2S Heater Resistance (Bank 1, Sensor 2)
P0141 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

Other than going back to 93 octane, any suggestions? Did the E30 harm/coat the O2 sensors? I sent a PM to some folks that started running E30 a long time ago to get feedback, but most of them aren't active members anymore.

Any help would be greatly appreciated.

 

[320icar]

I’ve never heard of e85 fouling o2 sensors, so I don’t see why e30 would.

 

[big jim]

did you replace the o2 sensor?

maybe it's the lack of driving the car (for longer periods of time) that is causing the o2 sensor to foul?

 

[JamoRS]

did you replace the o2 sensor?

maybe it's the lack of driving the car (for longer periods of time) that is causing the o2 sensor to foul?

I don't drive my car much, been on e30 for about 6 months, and haven't had any issues?

 

[lucky phil]

I started running E30 fuel late last year to boost the performance of my RS for autox duty. Amazing performance for such little annoyance of blending fuel every 2-3 weeks. Now I'm starting to have persistent O2 sensor heater codes pop up on the Cobb AP and cause a CEL. I do have a catless downpipe and a j-pipe restrictor. Currently at 6,142 miles.

Current codes:
P0030 - Faulty Heated Oxygen Sensor HO2S (Bank 1 Sensor 1)
P0054 - Faulty Heated Oxygen Sensor HO2S Heater Resistance (Bank 1, Sensor 2)
P0141 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

Other than going back to 93 octane, any suggestions? Did the E30 harm/coat the O2 sensors? I sent a PM to some folks that started running E30 a long time ago to get feedback, but most of them aren't active members anymore.

Any help would be greatly appreciated.

Sounds like the O2 sensor heater has failed Hank. Put a meter across the heater wires and check the resistance but bare in mind it may only go open when hot.
Ciao

 

[Hank]

I haven't replaced the O2 sensors yet. My plan is to check them like lucky phil suggests. I know they're 4 years old, but very low mileage.

 

[big jim]

I haven't replaced the O2 sensors yet. My plan is to check them like lucky phil suggests. I know they're 4 years old, but very low mileage.

i agree, they shouldn't be fouling at 7k miles...no way

 

[mj95cobra]

i agree, they shouldn't be fouling at 7k miles...no way

54k miles of E30 on my ST when I had it. Never a code.

 

[dmtalon]

Late to the thread, but been on E30 for a LONG time. 41k on the car, original O2

 

[JamoRS]

I started running E30 fuel late last year to boost the performance of my RS for autox duty. Amazing performance for such little annoyance of blending fuel every 2-3 weeks. Now I'm starting to have persistent O2 sensor heater codes pop up on the Cobb AP and cause a CEL. I do have a catless downpipe and a j-pipe restrictor. Currently at 6,142 miles.

Current codes:
P0030 - Faulty Heated Oxygen Sensor HO2S (Bank 1 Sensor 1)
P0054 - Faulty Heated Oxygen Sensor HO2S Heater Resistance (Bank 1, Sensor 2)
P0141 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

Other than going back to 93 octane, any suggestions? Did the E30 harm/coat the O2 sensors? I sent a PM to some folks that started running E30 a long time ago to get feedback, but most of them aren't active members anymore.

Any help would be greatly appreciated.

Who did your e30 tune?

 

[Hank]

Who did your e30 tune?

Tune+

 

[Hank]

Tested the resistance of the front/rear O2 sensors tonight. Did a brief search in the manual and could not find specified heater circuit resistance.
Front O2 sensor heater terminals (2 middle ones) had 3.3 - 3.4 ohms of resistance.
The rear O2 sensor heater terminals had an open circuit.
I will be ordering a rear O2 sensor tomorrow. Part #FB5Z-9G444-A

 

[lucky phil]

Tested the resistance of the front/rear O2 sensors tonight. Did a brief search in the manual and could not find specified heater circuit resistance.
Front O2 sensor heater terminals (2 middle ones) had 3.3 - 3.4 ohms of resistance.
The rear O2 sensor heater terminals had an open circuit.
I will be ordering a rear O2 sensor tomorrow. Part #FB5Z-9G444-A

Sounds like the problem Hank.

Ciao

 

[Hank]

New rear O2 sensor heater terminals tested at 3.3 ohms of resistance. I'm in a turnaround at work for the next few weeks, but I'll report back if the new rear O2 sensor eliminates the CEL.

 

[turbojr74]

New rear O2 sensor heater terminals tested at 3.3 ohms of resistance. I'm in a turnaround at work for the next few weeks, but I'll report back if the new rear O2 sensor eliminates the CEL.

It's not you running E30 Hank. I've been running 92oct the entire time. I have a catless DP and j-pipe restrictor....this just came up recently for me too
Those parts went on at 14,979 miles...

Add to the codes you have I also got:
P0036 - HO2S Heater control Circuit

Just turned 16k miles on MY18 and this car has sat here and there, but this is WAAAAAAAY too early for an O2 to go bad or its just rotten luck. Only been 1kmiles to have that one. That O2 isn't the easiest to get to either.

How much is Part #FB5Z-9G444-A costing ya? Is it really only $30?? I was expecting O2 to be $300-ish (last one I bought for my Evo).

 

[lucky phil]

It's not you running E30 Hank. I've been running 92oct the entire time. I have a catless DP and j-pipe restrictor....this just came up recently for me too
Those parts went on at 14,979 miles...

Add to the codes you have I also got:
P0036 - HO2S Heater control Circuit

Just turned 16k miles on MY18 and this car has sat here and there, but this is WAAAAAAAY too early for an O2 to go bad or its just rotten luck. Only been 1kmiles to have that one. That O2 isn't the easiest to get to either.

How much is Part #FB5Z-9G444-A costing ya? Is it really only $30?? I was expecting O2 to be $300-ish (last one I bought for my Evo).

Sometimes it's simply that.

Ciao

 

[turbojr74]

Sometimes it's simply that.

Ciao

Phil if you mean the rotten luck than for me and this car it’s been more than the Subie and Evo I’ve owned.
Just ugh....ly...

The bright side is if this sensor is $30...not where it’s located though.

 

[lucky phil]

Phil if you mean the rotten luck than for me and this car it’s been more than the Subie and Evo I’ve owned.
Just ugh....ly...

The bright side is if this sensor is $30...not where it’s located though.

I meant for the failed sensor but the experiences with the RS are varied. Some have zero issues and some lots. No idea the underlying reasoning but manufacturing quality and the fallout from leaving the head gasket replacement to the dealer network are big drivers I'd say. Add the variations thrown up by the questionable utility of modifications people have done and the competence with which they have been applied and there are some deep holes to fall into out there with this car.

Ciao

 

[Hank]

It's not you running E30 Hank. I've been running 92oct the entire time. I have a catless DP and j-pipe restrictor....this just came up recently for me too
Those parts went on at 14,979 miles...

Add to the codes you have I also got:
P0036 - HO2S Heater control Circuit

Just turned 16k miles on MY18 and this car has sat here and there, but this is WAAAAAAAY too early for an O2 to go bad or its just rotten luck. Only been 1kmiles to have that one. That O2 isn't the easiest to get to either.

How much is Part #FB5Z-9G444-A costing ya? Is it really only $30?? I was expecting O2 to be $300-ish (last one I bought for my Evo).

$47 + tax at my local Ford dealer. I wanted it quicker than waiting for Tasca.

 

[turbojr74]

$47 + tax at my local Ford dealer. I wanted it quicker than waiting for Tasca.

Any update on your side @Hank? I'm getting mine today and going to try and replace this weekend prior to Sunday if I'm lucky.