My Service Engine Soon light came on 2 days ago, and my 2004.5 G35 Sedan currently has ~47k miles on it. Two weeks ago, I did change the oil & rotated my tires, but I can't think of anything else that was recently done to the vehicle. The only mod I have is the MD 5/16 plenum spacer which I installed about 1.5 years ago.

This afternoon, I took the G35 to my local parts shop to scan my car. They actually found 2 codes:

P1148 Closed Loop, Bank 1
P1168 Closed Loop, Bank 2

They think this means that 2 of my 4 oxygen sensors need to be replaced, but couldn't tell which 2. Has anyone gotten these codes before? Any idea what I can expect to pay in parts and labor? Any idea what usually causes o2 sensors to fail?

About 10 mins ago, I went ahead and [successfully] cleared my CEL after checking out Msedanman's Easy Ecu Resetting thread. Was that a bad idea? Is it safe to continue driving around like this, or should I bite the bullet and get to the dealership right away?

Any feedback is greatly appreciated.

 

Closed loop is defined based off throttle position and the runs off of the O2 sensors on the exhaust manifolds.

The post-cat O2 sensors are strictly for emission purposes.

It sounds like you need to replace both of your O2 sensors UPSTREAM - on the headers/exhaust manifolds.

Resetting the ECU will not get rid of the problem and the CEL will return if the sensors do need to be replaced.

 

Thanks Tollboothwilley. I searched rockauto for upstream oxygen sensors, but couldn't tell which ones to order:

• BOSCH Part # 15730 {OE SmartLink - Universal Fit}
  Upstream; 2WD; 4 Wire; Heated; Check / Replace Interval: 100,000 Miles
  $48.79
  
• STANDARD MOTOR PRODUCTS Part # SG1405
  Upstream Sensor; RWD; 2 Required per Vehicle
  $102.99
  
• BOSCH Part # 15524 {OE Type - Exact Fit}
  Upstream; 2WD; 4 Wire; Heated; Check / Replace Interval: 100,000 Miles
  $124.79

Any recommendations?

 

Well, personally I just cut the wires and wire in a universal one. $60 vs $164 (local parts store cost). Makes sense. Some people don't mind paying the extra for the direct OEM fit...so it can clip right in. Its your call.

BTW, $48 for that seems like a great price.

 

I might actually buy 2 of those...i need to replace the sensors on the headers...I've got 150K miles on them.

 

Just a quick update: Since resetting my ECU over 2 years ago (ie, back on 12-04-2009), the CEL hasn't returned. Thanks g35driver for being such a fantastic resource!

 

Hello, I have a 2004 G35 6MT with 122k miles, two weeks ago the service engine light went on and it's been on since. I bought a bafx reader and got the P1148 fault code.what is the right procedure, take it to the dealer or a mechanic? How bad is this?