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671 Posts
Discussion Starter #1
On the Vulcan, '05 Taurus SE, what is the usual culprit to cause these? I've already replaced the seal on the transducer thing on the back of the intake plenum with an OEM part. I've about to hit 104k, so I'm sure something is dry rotted. I'm not in the mood to pull the intake manifold yet if I don't have to, it's hot down here. B)

3,748 Posts
DTC P2196 - Lack of HO2S-11 Switch, Sensor Indicates Rich. If you read the code carefully, you will see it does not indicate a bad HO2S-11, but rather the sensor is telling us it has sensed a rich fuel mixture. So you can change the HO2S-11 all day, and it will not fix anything. An HO2S indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.

So the HO2S-11 is working perfectly and is actually telling you the mixture is too rich. So what we need to do is address the rich fuel mixture problem. There can be a number of causes for this condition. The first thing I would check is the PCM wiring harness where it rests on the bracket at the right side front strut turret. Look at the underside of the harness (a mirror will help the inspection) and check for possible chafing on the cross car beam. If there are damaged wires, repair them as required. If it is a shielded wire that is damaged, you will need to replace the whole wiring harness. A shielded wire can not be repaired.

If the harness is okay, then we need to look at other possibilities. Some of these are:

* Short to VPWR in the harness or H)2S
* Water in the harness connector
* Open or shorted HO2S circuit
* Corrosion or poor mating terminal contacts or wiring
* Damaged HO2S
* Damaged PCM

Fuel System

* Excessive fuel pressure
* Leaking or dirty fuel injectors
* Leaking fuel pressure regulator
* Low fuel pressure or running out of fuel
* Vapor recovery system

Induction System

* Air leaks after the MAF
* Vacuum leaks
* PCV system
* Improperly seated dipstick or oil fill cap

EGR System

* Leaking EGR gasket
* Stuck EGR valve
* Leaking diaphragm or EVR

Base Engine

* Oil overfilled
* Cam timing
* Cylinder compression
* Exhaust leaks before or near the HO2S(s)

33 Posts
Could the CEL codes P2196 & P2197 be from a failing cam synchronizer? Its been chirping for the past year.
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