How to Diagnose and Fix a P0150 OBDII Trouble Code

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OBD2 error codes p0150

OBD2 Error Code: P0150  – What is it?

Matt here with Scanner Answers and today were talking about OBDII error codes. We spend a lot of time writing about wireless obd2 diagnostic tools and we’ve been getting requests to write about how to use diagnostic scanners. The P0150 code is what we’re dialing in on today and we hope this article helps you!

Oxygen sensors are some of the most common reasons people see a check engine light on their vehicle. A P0150 code indicates that there is an oxygen sensor circuit malfunction (bank 2, sensor 1). Essentially, the oxygen sensor circuit in question is not meeting the required voltage limits and could simply be a sensor circuit malfunction. The P0150 is a generic OBD DTC (Diagnostic Trouble Code) which can show up on Fords, Mercedes, BMW and nearly every vehicle in between that’s equipped with an OBD2 port.

So, what exactly is going on?

The ECM (engine control module) monitors voltage in the oxygen sensor which has a high and low limit set. If a P0150 code is showing, it means that the temperature sensor voltage is not falling inside of those sensor circuit low voltage or sensor circuit high voltage limits of the ECM control circuit.

Causes of the P0150 DTC

Shoutout to Justin for this awesome youtube video on the P0150 error

While this issue may not be cause for immediate problems, driving for too long could cause long-term issues. It’s best to resolve the problem now. Not to mention, the issue could force the engine to run rich, which is a wasteful way to consume fuel. You’re hurting your vehicle’s components and your wallet if you drive too long with this code.

Here are some of the most common causes of a P0150 code:

  • Corrosion in the connector
  • Loose connection between connector and terminal
  • Burnt wiring
  • Short in wiring
  • Vacuum leak
  • Exhaust leak
  • Oxygen sensor circuit malfunction
  • Oxygen sensor circuit slow response
  • Incorrect engine coolant temperature
  • The camshaft position
  • Failed PCM
  • Another circuit sensor malfunction, such as the sensor heater, or fuel temperature sensor

Oxygen Sensors

Your OBD2 scan tool should show the oxygen sensor switching rapidly between rich and lean. If not, there is a way to find out if the sensor is reading correctly or if there is another issue. Removing the fuel pressure regular vacuum supply for a moment should cause the oxygen sensor to read rich. Reinstall it and then remove the vacuum supply line from the intake manifold. Now the sensor should read lean. If the sensor is responding as expected then it is likely not the cause of this problem. However, if the sensor is not responding correctly it may need cleaning or replacing.

Loose Connections

If the sensor is working and the check engine light has come on intermittently then it would be best to start inspecting the wiring to the sensor. Any loose connections or corrosion could cause incorrect readings. If the connectors or terminals appear to need cleaning then some electrical contact cleaner should help to resolve the issue.

You can also test the voltages to the sensor. There should be 5V readings. If the sensor is not receiving the correct voltage, check for damaged or shorted wires and replace. If the sensor is receiving the correct voltage then it may need to be replaced.

Exhaust Leaks

Finally, the other most common issue is an exhaust leak. Holes in the exhaust may cause an incorrect reading from the oxygen sensor. Inspect the exhaust downstream from the oxygen sensor to ensure that there is no leak or damage. There could also be a vacuum leak in the engine causing this code.

Most often, the wiring is the cause of this code. Luckily, wiring can easily be inspected and you can choose to replace or repair any wiring that may be showing signs of wear or damage. Having a voltage meter handy will help make diagnosing the cause of a P0150 code easier.


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