The P0059: HO2S Heater Resistance (Bank 2, Sensor 1) code identifies a problem in the heater element of the oxygen sensor located in Bank 2, Sensor 1 of the engine. This sensor is responsible for helping manage the air-fuel mixture by measuring the amount of oxygen in the exhaust gases. A fault in the heater circuit can lead to incorrect readings, affecting the vehicle’s fuel efficiency and emissions.
P0059 quick overview
| Meaning | P0059: HO2S Heater Resistance (Bank 2, Sensor 1) |
| Is it serious? | This code indicates a potential issue with the oxygen sensor heater circuit, which can affect the vehicle’s emissions system and fuel efficiency. |
| Possible causes | – Faulty or failing oxygen sensor (Bank 2, Sensor 1) – Damaged, corroded, or loose wiring and connectors in the O2 sensor circuit – Issues with the oxygen sensor heater circuit, including fuse problems – Potential ECM (Engine Control Module) malfunction |
| How to diagnose? | Inspect O2 Sensor: Check the condition of the Bank 2, Sensor 1 oxygen sensor. Check Wiring and Connectors: Examine the O2 sensor’s wiring and connectors for damage or corrosion. Test Heater Circuit: Use a multimeter to test the heater circuit’s resistance and voltage. Scan for Additional Codes: Use a diagnostic scanner to identify any other related fault codes. Evaluate ECM: Consider the ECM for faults, especially if other diagnostic steps don’t reveal issues. |
P0059 Meaning
Code P0059 is a signal that there might be an issue with a specific part of one of your vehicle’s oxygen sensors, particularly the part that heats it. This can lead to problems with how the engine runs and how much fuel it uses. To fix it, you’ll need to check the sensor and the wires connected to it, and sometimes the issue can even be with the car’s computer system. It’s important to address this to ensure your car runs efficiently and doesn’t pollute more than it should.
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How to fix P0059 – learn from mechanics
I looked into P0059 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Ford
Vehicle Information: 2005 Ford Expedition Eddie Bauer 5.4L
Issue + Repair History:
- MIL lamp on.
- Two codes found: P0059 (HO2S21 Heater Resistance) and P2197 (O2S Stuck Lean).
- Replaced Bank 2 Sensor 1 oxygen sensor.
- Vacuum hoses checked for leaks.
- MIL returned on with code P2197 after test drive.
Other OBD2 Codes + Test Results:
- P0059: HO2S21 Heater Resistance.
- P2197: O2S Stuck Lean.
Exhaust Gas Readings:
- Idle: CO2 = 15%, O2 = 0.29%.
- Cruise: CO2 = 14.8%, O2 = 0.53%.
Suggestions to Fix Issue:
- Check if the mass sensor has issues or if there is a vacuum leak.
- Inspect PCV valve hose assembly for vacuum leaks.
- Use OEM oxygen sensors as aftermarket ones may not be reliable.
- Verify correct installation of the replaced oxygen sensor.
- Check for exhaust leaks at manifolds.
Final Fix:
- Replacing the upper intake manifold solved the problem.
Case #2: GMC
Vehicle Information: 2005 GMC Jimmy SLS 4.3L
Issue + Repair History:
- Engine light turns on intermittently.
- Sets codes P0053 and P0059 for heater resistance.
- Truck initially came in with new O2 sensors installed.
- Checked resistance of wires to PCM, found no problems.
Other OBD2 Codes + Test Results:
- P0053: Heater Resistance.
- P0059: Heater Resistance.
- Command heater on test: Heater working, voltage in range.
Suggestions to Fix Issue:
- Verify if O2 sensors are OE or aftermarket; preference for OE quality sensors.
- Check the O2 heater circuit resistance when cold, expected range 3+ to 9+ ohms.
- Test resistance of O2 sensors when both hot and cold, and compare.
- Ensure proper powers and grounds in the circuit.
- Consider the possibility of an ECM issue.
- Test current flow in the downstream sensor using a lab scope and a low current probe for comparison.
- Swap downstream sensor with an upstream sensor to confirm if the issue is sensor or PCM/voltage drop related.
Final Fix:
- Rechecked all wiring and replaced the O2 sensors again.
- Unclear why initial sensors were replaced; they were suspected to be the problem.
Case #3: Chevrolet
Vehicle Information: 2007 Chevrolet Express 1500 LS 5.3L
Issue + Repair History:
- MIL lamp on, no driveability problems.
- Codes related to the heater circuit of Bank 2 Sensor 1 O2 sensor.
- Ran O2 heater current test – all sensors in spec.
- Replaced sensor with new dealer sensor, but MIL returned after 2 days.
Other OBD2 Codes + Test Results:
- P0050: O2 Heater Control Circuit Bank 2 Sensor 1
- P0059: O2 Heater Resistance Bank 2 Sensor 1
- Heater current test: Passed warm.
- Sensor resistance: Good.
Suggestions to Fix Issue:
- Check fuses 39 & 40 in underhood power distribution box for moisture.
- Consider PCM issue if O2 sensor activity is not detected in less than 45 seconds after a cold start.
- Inspect O2A or O2B fuse if not open.
- Closely inspect wiring; consider PCM if everything else checks out.
Final Fix:
- Found that the control (ground) side of the sensor heater intermittently shorted to ground when harness near the back of the engine block was wiggled.
- Found two main ground splice packs on top of the intake manifold with bare copper wires shorting O2 heater control wire to ground.
- Fixed by addressing the poor heat shrink job on the harness.
Case #4: GMC
Vehicle Information: 2006 GMC Savana 3500 6.0L
Issue + Repair History:
- MIL lamp on, setting codes for O2 sensor heater resistance.
- Replaced all four O2 sensors and ECM over a year ago for the same problem.
- Checked wiring from sensors to ECM, resistance and voltage checked out.
- Aftermarket O2 sensors were used.
- Test light procedure for heater circuit did not produce expected results.
Computer Codes & Descriptions:
- P0053: B1S1 Heater Resistance
- P0059: B2S1 Heater Resistance
Other Test Results:
- Resistance on lo wire B1S1 and B2S1: .001 ohms.
- Voltage on pink wire: 12.30 volts.
Suggestions to Fix Issue:
- Use a lab scope to watch for pulse modulated heater circuit.
- Check resistance of O2 sensors when cold and hot, should be 1-3 ohms.
- Check connections at PCM and sensor harness for chafing of wires.
- Consider using only OEM sensors, as aftermarket ones may not meet original specs.
- Disconnect battery to relearn oxygen sensor heater resistor values.
- Swap terminals at underhood fuse block between bank 1 and bank 2 to test circuit.
- Use a low amps probe with a scope to monitor amperage.
Final Fix:
- Found that previously installed Bosch sensors were replaced with AC Delco sensors, which resolved the issue.
Case #5: Ford
Vehicle Information: 2010 Ford Explorer Sport Trac XLT 4.0L
Issue + Repair History:
- Multiple codes and stalling at a light reported.
- Initially cleared codes and checked for TSBs (none found).
- All parts shared the same power source.
- On recheck, all six codes returned.
- Found 12V KOEO, no voltage drop when wiggling harness.
- Resistance on EGR and purge solenoid within spec.
- Rear O2 heaters not active when upstreams were, during engine running.
- Function test on EGR showed all four heaters active.
- Test light on purge connector cycled on/off with no issue.
Computer Codes & Descriptions:
- P0053: O2 Heater Circuit
- P0054: O2 Heater Circuit
- P0059: O2 Heater Circuit
- P0060: O2 Heater Circuit
- P0403: Valve Position Control Circuit
- P0443: EVAP Management Fault
Suggestions to Fix Issue:
- Check splice 100 behind right head and connector 110 above R/F wheel well for corrosion.
- Consider the possibility of a PCM fault.
- Investigate any common feed to the heating side of O2 sensors and EGR solenoid.
- Check connectors at the fuse box.
- Examine power ground at the PCM.
Final Fix:
- Cleared codes; P0403 and P0443 wouldn’t clear.
- Monitored voltage change during KOER test; EVR dropped to 11V with slight RPM change, purge had no change.
- Vehicle taken to dealer; PCM replaced under warranty.
How to diagnose P0059
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Brief Description of Diagnostic Step |
|---|---|
| Check O2 Sensor Quality | Ensure the replaced O2 sensors are OEM or equivalent quality, as aftermarket sensors may not meet specifications. |
| Inspect Wiring and Connectors | Closely examine wiring harnesses and connectors for chafing, shorts, or corrosion, especially at key connection points. |
| Test Heater Circuit Resistance | Measure the resistance of the O2 sensor heater circuit, both cold and hot, to ensure it falls within the specified range. |
| Monitor Voltage and Grounds | Check for proper voltage supply and ground connections to the O2 sensors and related components. |
| Consider PCM/ECM Issues | If external circuits and components are in good condition, consider the possibility of a PCM (Powertrain Control Module) fault. |
| Perform Comprehensive Diagnostic Tests | Use advanced diagnostic tools, like a lab scope, to conduct thorough tests on O2 sensor circuits and monitor real-time data. |
| Follow Manufacturer’s Diagnostic Procedures | Adhere to the specific diagnostic procedures outlined by the manufacturer, including specialized tests like KOER. |
Car Diagnostics Training
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I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko