DTC Error Code P2270/P2272: Symptoms, Causes, and Solutions

1. Symptoms

• No noticeable driving issues (Sensor 1 is not affected)
• Malfunction Indicator Lamp (MIL) illumination
• In some cases, rough engine running

2. Potential Causes

The causes of this DTC may include:

• Exhaust leak near the oxygen sensor (O2)
• Contaminated or faulty HO2S2 oxygen sensor (Sensor 2)
• HO2S2 sensor wiring or circuit issue
• Loose installation of the HO2S2 sensor
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Defective purge solenoid valve
• Faulty PCM

3. Diagnostic and Repair Procedures

1. Visual Inspection
   • Inspect connectors and wiring for any corrosion, damaged wires, or bent pins.
   • Repair or replace faulty components.
2. Exhaust Leak Check
   • Identify and repair leaks as needed.
3. Connector Resistance Test
   • Use a digital ohmmeter (DVOM) to check the resistance of the harness connectors.
   • Compare values to manufacturer specifications.
4. Using an Advanced Scan Tool
   • Monitor HO2S2 sensor readings via the PCM (engine running, at normal temperature in closed loop).
   • A voltage stuck at 0V indicates a problem.
   • Revving the engine should cause the sensor voltage to vary.
5. Additional Checks
   • Inspect the HO2S2 sensor condition for contamination by fuel, engine oil, or coolant.
   • Test fuel pressure with a specific tester and compare to specifications.
   • Inspect the purge solenoid valve, injectors, and coolant passages for leaks.
6. Oxygen Sensor Replacement
   • If the sensor is faulty, replace it with an OEM sensor to ensure optimal compatibility and performance.

4. Additional Notes

• Ford TSB 14-0084: Applicable to certain F-150 (2010-2012), Navigator, Ranger, E-Series, and other models. Recommends replacing the O2 sensor for DTC codes P2270 or P2272.
• Chrysler/Dodge/Jeep TSB 18-011-08: Affects certain Compass, Patriot, Sebring, Avenger, and Caliber (2008-2010). If the DTC is intermittent, check if this bulletin applies to your vehicle. The fix involves reprogramming the PCM.
• Other Service Bulletins: Consult applicable TSBs for your make and model through your dealership or online sources.

By following these diagnostic and repair steps, you can identify and correct the source of DTC code P2270/P2272 to ensure proper engine operation.

Symptoms

You probably won’t notice any driving issues because it’s not sensor number 1. You will notice the Malfunction Indicator Lamp (MIL) lighting up. In some cases, however, the engine may run poorly.

Potential Causes

Causes

of this DTC may include:

• Contaminated or faulty HO2S2 (sensor 2)
• HO2S2 wiring/circuit issue
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect the wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.

Check for exhaust leaks or other issues, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connectors. Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor voltage to change (respond).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect the coolant passages for leaks.

Symptoms

You probably won’t notice any driving issues since it’s not sensor number 1. You will notice the malfunction indicator lamp (MIL) lighting up. In some cases, however, the engine may run poorly.

Potential Causes

Causes

of this DTC may include:

• Exhaust leak near the O2 sensor
• Contaminated or faulty HO2S2 (sensor 2)
• HO2S2 wiring/circuit problem
• Loose installation of HO2S2
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect the wiring and connectors for corrosion, rubbed/chafed/bent wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed. It would be a good idea to visually check the wiring of all sensors.

Check for exhaust leaks, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connector(s). Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). Look at the reading for bank 2, sensor 2. The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 0V. Revving the engine should cause the sensor voltage to change (react).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect the coolant passages for leaks.

There may be Technical Service Bulletins (TSBs) that apply to your make and model regarding this fault code; check with your dealership or online source to locate specific TSBs that apply to your vehicle.

Symptoms

You probably won’t notice any driving issues because it’s not sensor number 1. You will notice the Malfunction Indicator Lamp (MIL) lighting up. In some cases, however, the engine may run poorly.

Potential Causes

Causes

of this DTC may include:

• Contaminated or faulty HO2S2 (sensor 2)
• HO2S2 wiring/circuit problem
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.

Check for exhaust leaks or other issues, repair if necessary.

Using a digital volt ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connectors. Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor voltage to change (respond).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect coolant passages for leaks.

Symptoms

You probably won’t notice any driving issues since it’s not sensor number 1. You will notice the malfunction indicator lamp (MIL) lighting up. In some cases, however, the engine may run poorly.

Potential Causes

Causes of this DTC may include:

• Exhaust leak near the O2 sensor
• Contaminated or faulty HO2S2 (sensor 3)
• HO2S2 wiring/circuit issue
• Loose HO2S2 installation
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.

Check for exhaust leaks, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the harness connectors. Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 0V. Revving the engine should cause the sensor voltage to change (respond).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect coolant passages for leaks.

Symptoms

You probably won’t notice any driving issues since it’s not sensor number 1. You will notice the Malfunction Indicator Lamp (MIL) lighting up. In some cases, however, the engine may run rough.

Potential Causes

Causes of this DTC may include:

• Contaminated or faulty HO2S2 (sensor 3)
• HO2S2 wiring/circuit issue
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect the wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.

Check for exhaust leaks or other issues, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connectors. Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor voltage to change (respond).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect the coolant passages for leaks.

Symptoms

You probably won’t notice any driving issues because it’s not sensor number 1. You will notice the malfunction indicator lamp (MIL) lighting up. In some cases, however, the engine may run rough.

Potential Causes

Causes

of this DTC may include:

• Exhaust leak near the O2 sensor
• Contaminated or faulty HO2S2 (sensor 3)
• HO2S2 wiring/circuit problem
• Loose installation of HO2S2
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect the wiring and connectors for corrosion, rubbed/chafed/bent wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed. It would be a good idea to visually check the wiring of all sensors.

Check for exhaust leaks, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connector(s). Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). Look at the reading for Bank 2, Sensor 3. The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 0V. Revving the engine should cause the sensor voltage to change (react).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect coolant passages for leaks.

There may be Technical Service Bulletins (TSBs) that apply to your make and model regarding this fault code; check with your dealership or online source to locate specific TSBs that apply to your vehicle.

Symptoms

You probably won’t notice any driving issues because it’s not sensor number 1. You will notice the Malfunction Indicator Lamp (MIL) lighting up. In some cases, however, the engine may run rough.

Potential Causes

Causes

of this DTC may include:

• Contaminated or faulty HO2S2 (sensor 3)
• HO2S2 wiring/circuit problem
• Incorrect fuel pressure
• Faulty fuel injector
• Engine coolant leak
• Faulty purge solenoid valve
• PCM failure

Diagnostic and Repair Procedures

Visually inspect the wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.

Check for exhaust leaks or other issues, repair if necessary.

Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connectors. Compare to manufacturer specifications. Replace or repair as needed.

If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor voltage to change (respond).

The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.

If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.

Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect the coolant passages for leaks.

P2278 Possible Causes

• Faulty O2 sensor
• O2 sensor harness is open or shorted
• Poor electrical connection in the O2 sensor circuit

What Does It Mean?

How to Fix Code P2278

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

P2278 Symptoms

Check engine light on (or service engine soon warning light)

P2278 Meaning

O2 sensor signals swapped, bank 1, sensor 3 / bank 2, sensor 3 is the generic description for code P2278, but the manufacturer may have a different description.

Symptoms

An air leak is one of the least tolerated issues with a fuel-injected engine. The air/fuel ratio must be precisely controlled to function correctly. Symptoms of an engine code P2279 may include:

• Illumination of the Malfunction Indicator Lamp (MIL) with diagnostic code P2279 set
• Stalling at idle
• “Hunting” or surging at idle
• Lack of power
• Dead spots during acceleration
• ECM sets additional codes such as engine misfire in cylinder number 1
• Engine “knocking” due to lean mixture
• Cherry-red exhaust manifolds from an overly lean mixture
• Hissing sound produced by the air leak
• Increased resistance in power brakes (harder pedal)

Potential Causes

Potential causes of this engine code may include:

• Leak between the engine side of the mass air flow sensor and the air duct
• Air duct leak on the engine side
• Leak at the intake air temperature sensor
• Leak at the throttle body
• Crack or leak in the intake manifold
• Disconnected or broken vacuum hose
• Poor fuel injector seal to the manifold
• Leaking brake booster vacuum hose
• Leak under the dashboard on a vacuum-operated device
• Stuck PCV valve
• Stuck oil filler cap
• Anything and everything connected to the intake manifold could potentially cause this scenario.

Diagnostic and Repair Procedures

• First, start the engine and open the hood. Listen for a hissing sound and trace it back to its source. Repair it if necessary. A heater hose held to your ear works well.
• Perform a propane test. Remove the nozzle from a propane torch and install a rubber vacuum hose. Start at the mass air flow sensor and work toward the intake manifold, directing a small amount of propane toward all suspected devices.
• There will be a dramatic change in idle speed when the leak source is located.
• Run the propane hose all around the air ducts leading to the throttle body and intake manifold.
• Check for an interior vacuum leak under the dashboard. Do not use propane; listen. Often, one of the vacuum motors for the HVAC doors has come loose.

NOTE: Be cautious when using unlit propane to find a leak; we are not responsible for any damage or injury that may result from its use! If you are unsure about using it, you can also spray carburetor/choke cleaner on suspected areas. Or, build your own smoke machine. There are alternatives to using propane.

Once the leak is detected and fixed, use a common code scanner to clear the code and reset the ECM.

This code may apply to any vehicle from 1996 onward, but it appears to be more common on Vauxhall, Saab, Honda, Acura, and VW.