Multiple Codes

[sheltonfilms]

My brother in law has a 2002 Explorer 4.0 (K engine) and his truck is throwing the following codes:

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean

Below codes are pending codes:
P0153 - Oxygen Sensor Circuit Slow Response (Bank2, Sensor1)

P0172 - System Too Rich Bank 1

P0174 - System Too Lean Bank 2

Most of these suggest the Bank 2 Sensor 1 is the culprit, but what is throwing me off is the P0172 code. Maybe its just a coincidence.

What do you guys think?

 

[imp]

My brother in law has a 2002 Explorer 4.0 (K engine) and his truck is throwing the following codes:

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean

Below codes are pending codes:
P0153 - Oxygen Sensor Circuit Slow Response (Bank2, Sensor1)

P0172 - System Too Rich Bank 1

P0174 - System Too Lean Bank 2

Most of these suggest the Bank 2 Sensor 1 is the culprit, but what is throwing me off is the P0172 code. Maybe its just a coincidence.

What do you guys think?

Is the truck running poorly, or normally? imp

 

[sheltonfilms]

He has complained that his gas millage has gone down significantly.

 

[imp]

P0172 may not be related to the primary issue. Depending on age/mileage, I would replace the oxygen sensor. imp

 

[sheltonfilms]

I erased the codes and the pending ones didn't come back, so they must have been one time occurrence.

I went ahead and changed the HOS2-2,1 sensor, so lets see how it reacts after a few drive cycles.

I'll post results after a few days of driving.

 

[imp]

I erased the codes and the pending ones didn't come back, so they must have been one time occurrence.

I went ahead and changed the HOS2-2,1 sensor, so lets see how it reacts after a few drive cycles.

I'll post results after a few days of driving.

As I understand things, if an intermittent fault occurs rarely, it will not likely throw a code, something like a hundred or more repeat "trouble sightings" of the same type must occur to repeat throwing a code.

So, if something's sticky, now and then, like an EGR valve moves OK, then doesn't one time, then does, no code thrown. imp

 

[sheltonfilms]

Update: No more codes so the O2 must have been bad or degrading.