P0044 on 2013-2016 Jaguar XJ: HO2S Heater Circuit High (B1S3) Causes and Fixes

What's Unique About the 2013-2016 Jaguar XJ

For the 2013-2016 Jaguar XJ (X351 generation), this is a standard OBD-II code. However, Jaguar has issued several Technical Service Bulletins (TSBs), including JTB-00392-NAS-3, that identify a software error in the Powertrain Control Module (PCM) as a potential cause for P0044 and a host of related HO2S codes. This bulletin recommends a PCM software update as a specific fix, suggesting the issue is not always a hardware failure. This is a significant distinction from many other vehicles where the sensor itself is the sole culprit.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on.
• Vehicle may fail an emissions test.
• Slightly reduced fuel economy.
• Possible rough idle or hesitation for a few moments on a cold start.

Most Likely Causes

1. Failed Bank 1, Sensor 3 Oxygen Sensor 🔴 High Probability → Shop Oxygen Sensor The internal heater element within the oxygen sensor is a common failure point due to constant heat cycles and exposure to exhaust gases. Jaguar Land Rover platforms of this era have TSBs (like SSM63157 for Land Rover) citing manufacturing faults and susceptibility to thermal shock in the sensors themselves.
   How to confirm: Disconnect the sensor and measure the resistance across the two heater circuit pins (typically the two same-colored wires) with a multimeter. A good heater should have a resistance between 2-20 ohms. An open circuit (infinite resistance) or a dead short (near zero resistance) confirms the heater has failed.
   Typical fix: Replace the Bank 1, Sensor 3 oxygen sensor. 🎬 Watch: A quick guide to fixing the P0044 code. This requires a 22mm (or 7/8 inch) slotted oxygen sensor socket. Applying anti-seize compound to the new sensor's threads is recommended.
   Est. part cost: $70 - $250
2. Powertrain Control Module (PCM) Software Error 🟡 Medium Probability → Shop Engine Control Module (ECM) Jaguar TSB JTB-00392-NAS-3 explicitly states that a software error can cause this and other related HO2S codes. The fix is to update the PCM software using dealer-level diagnostic tools.
   How to confirm: This can only be confirmed by a Jaguar dealer or a specialist with access to TOPIx and the appropriate diagnostic equipment (SDD/Pathfinder) 🎬 See how to set up SDD for module programming. to check the current software version against the latest available version mentioned in the TSB.
   Typical fix: Update the Powertrain Control Module (PCM) to the latest software version.
   Est. part cost: $0 - $250 (cost of dealer labor for programming)
🎬 Watch: How a PCM reflash is performed using SDD.
3. Wiring Short to Power ⚪ Low Probability The wiring harness runs close to hot exhaust components, and the insulation can become brittle and crack over time, leading to a short circuit. The harness for Sensor 3 is routed under the vehicle, exposing it to potential road debris and moisture.
   How to confirm: Visually inspect the wiring harness leading to the O2 sensor for any signs of melting, chafing, or contact with the exhaust or driveshaft. With the sensor disconnected and the key on, use a multimeter to check for voltage on the heater control wire from the PCM; it should not have constant battery voltage.
   Typical fix: Repair or replace the damaged section of the wiring harness and secure it away from heat sources.
   Est. part cost: $10 - $100

Rare But Worth Checking

• Powertrain Control Module (PCM) Hardware Fault: → Shop Engine Control Module (ECM) This is the least likely cause. The driver circuit within the PCM that controls the sensor heater can fail, but the known software issue and sensor/wiring failures should be ruled out first before condemning the PCM.

Diagnosis Steps

1. Use an OBD-II scanner to confirm P0044 is the active code and check for any other related codes. Review freeze-frame data.
2. Check for applicable Technical Service Bulletins (TSBs), specifically JTB-00392-NAS-3, which points to a potential PCM software update as the solution.
3. Visually inspect the wiring harness and connector for the Bank 1, Sensor 3 oxygen sensor (passenger side, rearmost sensor). Look for any signs of melting, corrosion, or physical damage.
4. Disconnect the sensor and inspect the connector pins for damage or corrosion.
5. With the key on and engine off, check for battery voltage at the power supply wire in the sensor's harness connector.
6. Measure the resistance of the heater circuit within the oxygen sensor itself using a multimeter. A reading outside the manufacturer's specification (typically 2-20 ohms) indicates a faulty sensor.
7. If the sensor and wiring are good, the issue is likely the PCM software error described in the TSB. Professional diagnosis and programming are recommended at this stage.

Parts You'll Likely Need

• Oxygen Sensor (Bank 1, Sensor 3) (OEM #C2P16397) — This is the most frequent hardware cause of a P0044 code, as the internal heater element fails. This part number fits downstream positions on many 2010-2015 Jaguar 5.0L V8 models, including the XJ, XF, and XK.
  Trusted brands: Bosch, Denso, NGK/NTK, Walker
  OEM price range: $195 - $378
  Aftermarket price range: $70 - $120

Related Codes That Often Appear With This One

• P0042 — Relates to the heater control circuit being low for the same sensor (Bank 1, Sensor 3).
• P0043 — Relates to the heater control circuit being low for the same sensor (Bank 1, Sensor 3).
• P0144 — Relates to the sensor circuit having high voltage for the same sensor (Bank 1, Sensor 3), indicating a potential related issue.

Technical Service Bulletins (TSBs) & Recalls

• SSM72477: Mentions P0044 in a list of faults related to pre, mid, or post catalyst heated oxygen sensors.
• JTB-00392-NAS-3: The most critical TSB. It identifies a PCM software error as a direct cause for P0044 on 2013-2015 models and instructs technicians to perform a software update as the repair.
• JTB00392NAS1: An earlier version of the above TSB, also listing P0044 as a relevant DTC for HO2S issues that may be software-related.

Platform-Specific Known Issues

• Jaguar issued TSB JTB-00392-NAS-3 for 2013-2015 XJ, XF, and F-Type models with the 3.0L V6 or 5.0L V8, stating that P0044 (and many other O2 sensor codes) may be caused by a software error. The prescribed fix is to update the PCM software.
• Owners on forums frequently confuse the location of the six different oxygen sensors. Bank 1 is the passenger side (US), and Sensor 3 is the final sensor in the exhaust stream, located post-catalytic converter, often near the center of the car where the downpipe and mid-pipe connect.

Mechanic-Grade Diagnostic Values

• HO2S Heater Element Resistance — expected: 3-20 Ohms, with a target of approximately 8 Ohms on many applications.. Failure: Infinite resistance (open circuit) or near-zero resistance (short circuit).
• HO2S Heater Power Supply Voltage — expected: 11-14 Volts (Battery Voltage) with Key On, Engine Off.. Failure: Absence of voltage indicates a problem with the fuse, relay, or power feed wiring.
• HO2S Heater Circuit Current Draw — expected: 0.5 - 3.0 Amps when commanded ON by the PCM.. Failure: No current draw indicates an open circuit; excessive current indicates a short.
• Engine Ground Point Voltage Drop — expected: Well under 0.5V (500mV).. Failure: A reading higher than 0.5V indicates a poor ground connection that can cause various electrical issues.

Hidden / Shadow Codes Worth Checking

• Mode 6 Data (e.g., Test ID $3B): Mode 6 provides test results for non-continuously monitored systems, including O2 sensor heaters. A failing test result can appear here before a full-blown DTC like P0044 is triggered. (see via An advanced OBD-II scan tool that can access Mode 6 data. The specific Test ID (TID) and Component ID (CID) for the B1S3 heater must be looked up for the specific vehicle, but this data can reveal misfire-like counts for the heater circuit's performance.)
• Unrelated Events (in SDD): In Jaguar's Symptom Driven Diagnostics (SDD), if a technician does not select symptoms that lead to this code, it may be stored in a log of 'Unrelated Events'. Reviewing this section can reveal codes the primary diagnostic path might have missed. (see via Jaguar SDD dealer-level diagnostic software.)

Scan Tool Commands That Help

• Jaguar SDD (or equivalent advanced scanner): Oxygen Sensor Heater Active Test — This bidirectional command allows a technician to manually turn the B1S3 heater circuit on and off. It is used to verify if the PCM driver is working and to observe the voltage drop and current draw in real-time, confirming the integrity of the entire circuit from the PCM to the sensor.
• Jaguar SDD: Vehicle Reset — After performing a repair, such as replacing a sensor or updating software, a 'vehicle reset' should be performed to clear adaptations and ensure all modules recognize the new state of the system.

Wiring & Ground Locations

• Engine Compartment Fuse F12 (Bank A) — In the engine compartment fuse box.. On 2016-2019 models, this 10A/20A fuse protects the 'Oxygen sensors Bank A' (Bank 1). A blown fuse here will disable the heaters for the entire bank, causing heater circuit codes.
• Engine Grounding Strap — Located directly under the starter on the right (passenger) side of the car, connecting the transmission/engine block to the frame.. A poor main engine ground can cause a host of erratic electrical issues, including incorrect voltage readings in sensor circuits. Performing a voltage drop test on this ground is a key diagnostic step.
• B1S3 Connector Pins — At the sensor body, connecting to the main harness.. Knowing the pin functions is crucial for testing. While specific to an X-Type, a common Jaguar wiring scheme for downstream sensors is: Pin 2 (White/Green wire) for heater power and Pin 1 (Blue wire) for the PCM-controlled heater ground. This should be verified on the XJ with a wiring diagram.

Real Owner Repair Stories

• JaguarForums.com user with an XJS (Jaguar XJS (older model, but demonstrates a relevant electrical failure pattern)) — O2 sensor heater circuit fault after wires shorted out.
  ❌ Tried (didn't work) Testing the power wire from the fuel pump relay showed 12V, but it dropped to 0V when the sensor was plugged in, indicating a weak power feed unable to handle the 3-amp load.
  ✅ What actually fixed it The owner bypassed the original weak power feed. He tapped into the A/C fan relay circuit, added a 10-amp fuse, and ran a new wire through the firewall to power the O2 sensor heater directly. He also created a new, solid ground for the heater's ground wire.
• JaguarForums.com user with an XJ8L (2005 Jaguar XJ8L) — Error codes for all four oxygen sensors failing at the same time.
  ❌ Tried (didn't work) The dealer initially assumed all four sensors were bad and replaced them.
  ✅ What actually fixed it The root cause was a failed relay that powered the heater circuits. The faulty relay had burned out the original sensors. The final fix was replacing the bad relay in addition to the new sensors.

OEM Part Supersession History

• C2P16397 → N/A — This part number is specified for 5.0L models up to VIN V39426.
  Heads up: Vehicles after VIN V39426 may use a different part number. It is critical to verify the part number against the vehicle's specific VIN before ordering.

Model Year Variations Within This Range

• 2013-2015: These model years are specifically called out in TSB JTB-00392-NAS-3 as potentially having a PCM software error that causes code P0044. The recommended fix is a software update.
• 2016-2019: The engine compartment fuse box layout identifies specific fuses for the oxygen sensor banks (F12 for Bank A/1, F13 for Bank B/2). This may differ from the 2013-2015 models, which might have the heaters powered by a different fuse or relay.