A little redundant

[CLASSVT]

The other day I got a P0153 and P1151. Thing is.. I replaced that O2 sensor about three weeks ago with a new Denso sensor. Why would I get these codes again? Thanks in advance.

 

[projectSHO89]

So, which sensor was it that you replaced?

Steve

 

[CLASSVT]

I replaced the one on my headers.

 

[Tony2005]

I replaced the one on my headers.

ROTFL. Maybe needs a little more description. Did you replace the Bank 1 (firewall side) Upper, Bank 1 (firewall side) Lower, Bank 2 (radiator side) Upper or Bank 2 (radiator side) Lower?

 

[CLASSVT]

ROTFL. Maybe needs a little more description. Did you replace the Bank 1 (firewall side) Upper, Bank 1 (firewall side) Lower, Bank 2 (radiator side) Upper or Bank 2 (radiator side) Lower?

Sorry, forgot about the firewall side. It was radiator side and it was on my headers near the location of the oil filter. Does that make it Bank 2 lower? I just replaced the one in that infamous picture that you always post. So, back to the point... what could cause that CEL after the O2 was just replaced?

 

[Tony2005]

... It was radiator side and it was on my headers near the location of the oil filter. Does that make it Bank 2 lower? I just replaced the one in that infamous picture that you always post. So, back to the point... what could cause that CEL after the O2 was just replaced?

On that 2-D picture, the one on the left (closest to filter in that 2-D picture) is the Bank 2 Upper. Standing in front and looking down, you will reach the one on the left first (hence Upper sensor). That is the correct O2 sensor to replace for those codes.

However, as you are getting the codes again, you need to look at other issues. Vacuum leaks (UIM, LIM gaskets), exhaust leaks, maybe even the headers are causing the problems for all you know (if the PCM/O2 sensor sees the headers as a restriction in the airflow), although I highly doubt it.

Edit. From TSB,

P0153 - HO2S Sensor Circuit Slow Response (HO2S-21)The HO2S monitor checks the HO2S sensor frequency and amplitude. If during testing, the frequency and amplitude were to fall below a calibrated limit, the code will set.
Electrical:
· Shorted/open wiring
· PCM
Induction System:
· MAF sensor (On 4-cylinder engines, if P0133 is present, this could be caused by a MAF issue - on 6- and 8-cylinder engines, this could only be a MAF issue if P0133 and P0153 are both present)
· Inlet air leaks (unmetered air)
Fuel Concerns:
· Poor fuel quality
Base Engine:
· Exhaust leaks (upstream or near HO2S)
HO2S Concerns:
· Contaminated HO2S sensor (contamination from the use of silicone-based cleaners and sealants, leaded fuel, excessive oil consumption, etc.)
· Deteriorating HO2S sensor

P1151 - Lack of HO2S-21 Switch, Fuel Trim at LimitThe HEGO Sensor is monitored for switching. The code will set when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

Electrical:
· Short to VPWR or VREF in harness or HO2S
· HO2S circuit shorted to Ground
· Water in harness connector
· Open circuit
· Corrosion or poor mating terminals and wiring
· Damaged HO2S
· Damaged PCM (other DTCs should be present)
Fuel System:
· Excessive fuel pressure (stuck fuel pressure regulator, restricted fuel return lines, etc.)
· Leaking/contaminated fuel injectors or fuel pressure regulator
· Low fuel pressure or running out of fuel (fuel pump concern, fuel supply line restrictions, low fuel level, etc.)
· Vapor recovery system (stuck VMV, etc.)
Induction System:
· MAF contamination
· Air leaks between MAF and throttle plate
· PCV system / Other vacuum leaks
· Improperly seated engine oil dipstick
EGR System:
· Leaking gasket
· Stuck EGR valve / Leaking diaphragm or EVR
Base Engine:
· Oil overfill
· Incorrect cylinder compression
· Exhaust leaks before or near the HO2S
· Secondary air stuck on

 

[CLASSVT]

Well I know the seal btwn my K&N and MAF adapter isn't great. But that would still be metered air, so is it safe to rule that out? I have no idea where I could have a vacuum leak. All IM gaskets are new from rebuild. Maybe time for new tb gasket?

 

[Tony2005]

Spray gaskets, hose clamps and joints, with carb cleaner. If idle changes, you found your leak. And yes, maybe time for some new gaskets (especially the ones which weren't changed during the rebuild). In addition, torque bolts (off those removed and reinstalled recently) to specs and see if that helps.