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P2270 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P2270 is an OBD-II Code that refers to O2 Sensor Signal Stuck Lean Bank 1 Sensor 2


A P2270 code is caused by an ECM (Engine Control Module) receiving a signal that the O2 sensor signal is stuck lean on bank 1 sensor 2. There are three possibilities: the O2 sensor in bank 1, sensor 2 is indicating either too much oxygen in the exhaust air, an open circuit, or a faulty sensor that results in a lean signal to the ECM.


Common causes for this code include:

  • Leakage of the cooling system liquid.
  • A wiring or circuit issue with the H02S2.
  • Incorrect installation of HO2S2.
  • The fuel injectors are faulty.
  • Contaminated or failed HO2S2 (Sensor 2).
  • Fuel pressure not within correct parameters
  • A purge solenoid valve is broken.
  • Around the O2 sensor, there is a leak of exhaust.
  • The PCM has failed.


The symptoms of a P2270 code are:

  • Check Engine Light on.
  • Poor fuel economy.
  • Problems pertaining to the catalyst converter


To diagnose a P2270 DTC code, a technician would:

  1. Examine all wiring and connectors for open or high resistance.
  2. Inspect all vacuum hoses for damage or other engine intake leaks.
  3. Check the fuel pressure to ensure it is within specification.
  4. Confirm HO2S signal continuity by checking voltage between ground circuit and any combination of terminals 1, 2, 3 while HO2S is enabled.
  5. Reconnect any connectors that have been disconnected recently. 
  6. Test drive vehicle to see if the problem comes back. 

Common mistakes

The following are common mistakes when diagnosing the trouble code P2270:

Replacing Oxygen Sensor before electrical tests of the sensor.

No faults found during testing, therefore, no repairs made and the vehicle is left with code present.

ECM (Engine Control Module) not tested for faults after it has been diagnosed as faulty.

How serious is this?

A P2270 code is by no means an end-of-the-world repair. It is mainly an inconvenience. However, in some cases the engine may run rough.

What repairs can fix the code?

The following are solutions that may fix this problem:

  1. The most common fixes for this DTC seem to be either an exhaust air leak, a wiring problem with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an OEM one (manufacturer brand) for best results. 
  2. Corrosion, rubbed / chafed / bent wires, wiring pins bent/loose, burnt appearance, and/or crossed wires should all be visually inspected.
  3. Then, using a digital volt ohm meter (DVOM) set to ohms, inspect harness connections for resistance. Check the resistance of each harness connector against the manufacturer’s specifications.
  4. Using a fuel pressure tester, check the valve on the gasoline rail’s fuel pressure.
  5. If you take out the HO2S oxygen sensor, clean it for fuel, engine oil, or coolant residue.
  6. Check for any leaks in the purge solenoid valve. Examine the fuel injectors. Look for drips in the cooling system.

Related codes

A P2270 is related to and may be accompanied by the following codes: 

P0171, P0174, P2269, P0449

How much does it cost to fix the P2270 code?

The repair cost of a P2270 code depends entirely on how quickly you take your vehicle to a mechanic after the light comes on. If you have an extended warranty plan, make sure to use it.

If you go to a shop and they charge you a diagnostic fee, generally it’s about $100-$200 for a standalone P2270 code diagnosis.

Estimated total: $200 – $300 USD (parts and labor). However, if part(s) need replacing, prices may vary depending on the dealer/shop used. If multiple codes are present in conjunction with one another, the price will most likely go up.


In conclusion, the P2270 code is not that bad at all. If the vehicle is running fine it may not need urgent attention. However, if there are any other problems with the vehicle or noticeable performance issues (i.e., hesitation in acceleration), definitely get it checked out sooner rather than later. The more serious consequence of a malfunctioning O2 sensor is the effect it has on the fuel economy and spark plugs as mentioned earlier.

P2270 Code – What Does It Mean & How To Fix It