P2197: O2 Sensor (Bank 2 Sensor 1) – Signal Stuck Lean

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P2197 is a general DTC code that indicates that the signal coming from the first O2 sensor on the bank two side of the engine is stuck giving off a lean signal.  The voltage reading from a normal oxygen sensor should look something like a heartbeat, whereas with P2197 the voltage looks like a low voltage flatline).

P2197 is a general code, which means that it has the same meaning for any make, model, or year.  It is most typically caused by a bad O2 sensor, but there can A LOT of issues that can cause this code.  You will need to know how to find bank 2, which you can do by clicking here.

P2197 Symptoms

The symptoms associated with P2197 can be varied.  Often, the check engine light will be the only symptom.

  • Check engine light
  • Rough running engine
  • Misfire
  • Hard/Rough start
  • Difficulty idling

P2197 Common Causes

P2197 Causes

  • Oxygen Sensor– The B2S1 oxygen sensor could be bad, or the wiring going to/from it could have issues.  The wiring that goes to all of the O2 sensors is some of the most error prone on any vehicle.  It gets more exposure to the elements and heat, which can lead to an open/short situation.
  • Bad Sensor– The PCM relies on the MAF, ECT, A/F sensors to help it adjust the air/fuel ratio.  When they go bad, it may force the air/fuel mixture to lean out, which in turn can throw P2197.
  • Vacuum Leak– A vacuum leak allows UNMETERED air to enter into the combustion chamber, changing the air/fuel mixture.
  • Fuel System– A bad fuel injector or the wrong fuel pressure can cause P2197.
  • Exhaust Leak– An exhaust leak allows the exhaust to exit somewhere other than the tailpipes.  If there is too much exhaust that is allowed to leave, it’ll show up as a lean condition.

P2197 Diagnosis

P2197 Diagnosis

Here are some diagnostic steps that you can use to diagnose this code from home.

Capture the Short/Long Term Fuel Trim Values

If you happen to have access to a scan tool, you can use it to capture the short and long term fuel trim values.  You’ll need to make sure that the engine is warmed up before you do this.  

Doing this will help you determine if the O2 sensor is operating within spec without having to do any looking under the hood.  

While this isn’t a skill most DIY mechanics have, the concept is simple, and you can learn enough to use fuel trim to your advantage by watching this 11 minute video (it’s worth it). 

Swap Test

Since you have a V6, V8, or V10 engine,  there are two cylinder banks, which means you can do the swap test to determine if the bank 2 sensor 1 oxygen sensor is bad.  You just swap the bank 1 and bank 2 oxygens sensors.  Here’s what you do.

  1. Clear the codes with your scanner.
  2. Swap the Bank 2 Sensor 1 O2 sensor with the Bank 1 Sensor 1.  It’ll be on or right after the exhaust manifold.
  3. Run the engine until the check engine light comes back on. 
  4. If the code changes to P2195 (which indicates the O2 sensor on Bank 1 is stuck lean), that is enough proof that you need a new O2 sensor.
  5. If the code remains P2197, you’ll need to continue pursuing your diagnosis, knowing that both O2 sensors are working fine.

Check the O2 Sensor Harness

You can use a multimeter to check for any short or open circuits at the wiring harness.  A quick visual inspection can often tell you if there is something wrong, but not in the way the use of a multimeter will.

Vacuum Leaks

Often a worn or brittle vacuum line will allow unmetered air into the engine.  When this happens, it creates a lean condition.

You can test for a vacuum leak around the vacuum lines and the intake manifold.  A common method is to spray carb cleaner around the intake/vacuum lines.  When the spot is found the engine will rev higher with no throttle input.

Obviously, carb cleaner is super flammable.  So be CAREFUL.  Make sure you have a form of fire suppression available to you.

Fuel Issues

Since you have an engine with 2 banks (not an inline engine) and you’re getting P2197 without getting P2195, it could mean that an injector has gone bad. If there was a fuel pressure issue, you’d likely get P2195.  

Further Testing

If you’ve looked over all of the items listed above, and you still haven’t diagnosed P2197 in your vehicle, don’t give up.

  • Take a look at the MAF and IAT sensors.  They could be telling the engine the wrong amount of air is entering the combustion chamber.
  • Check to see if there are any TSB’s for your engine and model year.

P2197 Conclusion:  Usually the O2 Sensor

P2197 can be caused by a lot of issues, you’ll more than likely be replacing an oxygen sensor though.  Good luck diagnosing your vehicle!