P0202 on 2014-2016 Mazda MAZDA6: Injector Circuit Malfunction Causes and Fixes

What's Unique About the 2014-2016 Mazda MAZDA6

For the 2014-2016 Mazda6, code P0202 has a specific and important history documented by Mazda itself. A Technical Service Bulletin (TSB #01-017/16) reveals that an internal failure within the DENSO-made Powertrain Control Module (PCM) can cause this code, often paired with P0203 for the adjacent cylinder. This TSB applies to vehicles built before May 23, 2016, with VINs lower than JM1GJ**484154. This means that while a single bad injector is a possibility, a dual-code situation (P0202 and P0203) strongly points towards a faulty PCM, a unique and critical diagnostic clue for this specific vehicle and its platform mates like the Mazda3 and CX-5.

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 (may be flashing in severe cases)
• Rough or uneven idle
• Engine hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Poor fuel economy
• Engine misfiring, which may feel like a shake or shudder
• Strong fuel smell from the exhaust due to unburned fuel

Most Likely Causes

1. Faulty Fuel Injector 🔴 High Probability → Shop Fuel Injector
   How to confirm: The most reliable method is to swap the cylinder 2 injector with another one (e.g., cylinder 1). If the trouble code changes to P0201, the injector is confirmed to be faulty. You can also test the injector's internal resistance with a multimeter; the specification is approximately 1.6–2.52 ohms at operating temperature. A reading of infinity (OL) or zero indicates a failed injector. 🎬 Watch: How to test your Mazda fuel injector with a multimeter.
   Typical fix: Replace the faulty fuel injector. 🎬 See these Skyactiv injector removal tips and tricks before starting.
   Est. part cost: $50-$311
2. Internal Powertrain Control Module (PCM) Failure 🟡 Medium Probability → Shop Engine Control Module (ECM) Mazda issued TSB #01-017/16 for this specific issue on vehicles built before May 23, 2016, with a DENSO-produced PCM. The bulletin states an internal failure can cause injector circuit codes for cylinders 2 and 3 (or 1 and 4) to appear together.
   How to confirm: This is the likely cause if P0202 appears simultaneously with P0203. A diagnostic scan showing both codes is the primary indicator. A technician would also verify the PCM is a DENSO unit as described in the TSB before recommending replacement.
   Typical fix: The PCM must be replaced with a new or remanufactured unit and programmed to the vehicle. Mazda notes that the part numbers for the PCM were not changed, but the internal fault was corrected in later production units.
   Est. part cost: $200-$800 (Remanufactured), $900+ (New OEM)
3. Wiring or Connector Issue ⚪ Low Probability Standard heat and vibration in the engine bay can cause wires to chafe or connector pins to corrode over time.
   How to confirm: Visually inspect the wiring harness and connector for cylinder 2's injector for any signs of damage, corrosion, or loose pins. Use a multimeter to check for continuity to the PCM and for 12V power at the connector. A noid light can also be used to verify the PCM is sending a pulse signal. 🎬 Watch this quick guide on diagnosing and fixing code P0202.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the connector.
   Est. part cost: $5-$50

Diagnosis Steps

1. Scan for Codes: Use an OBD-II scanner to confirm P0202 and check for any other codes, especially P0203 or P0302.
2. Check the TSB: If P0202 and P0203 are present together, immediately suspect a PCM failure as described in TSB #01-017/16. Verify the vehicle's VIN and build date against the bulletin's criteria.
3. Visual Inspection: Examine the wiring and connector for the cylinder 2 fuel injector. Look for any broken wires, corrosion, loose pins, or heat damage.
4. Test the Injector Resistance: Disconnect the injector and use a multimeter to measure its internal resistance. It should be between 1.6 and 2.52 Ohms. If it reads as an open loop (OL) or has zero resistance, the injector has failed internally.
5. Swap the Injector: If only P0202 is present and the resistance is questionable, swap the injector from cylinder 2 with one from another cylinder (like cylinder 1). Clear the codes and run the engine. If the code returns as P0201, the injector is bad. If P0202 returns, the problem is in the wiring or PCM.
6. Check the Circuit with a Noid Light: If the injector swap doesn't move the code, use a noid light on the cylinder 2 injector connector. Start the engine and watch the light. If it flashes steadily, the PCM driver and wiring are likely good, pointing back to an intermittent injector issue. If it does not flash, the problem is in the wiring or the PCM itself.

Parts You'll Likely Need

• Fuel Injector (OEM #PY01-13-250) — This is the most common component to fail when P0202 appears alone. The internal coil can fail, creating an open or short in the circuit. This part number is applicable to the 2.5L engine in the Mazda6, Mazda3, and CX-5 for these model years.
  Trusted brands: Mazda OE, Bosch, Denso
  OEM price range: $210-$311
  Aftermarket price range: $50-$150
• Powertrain Control Module (PCM) (OEM #****-18-881* (Varies by VIN)) — A known issue documented by Mazda TSB #01-017/16 makes this a likely culprit, especially if P0202 is paired with P0203. The TSB notes to order the latest part number applicable to the vehicle's VIN.
  Trusted brands: Mazda OE, Remanufactured (e.g., Flagship One, Circuit Board Medics)
  OEM price range: $900-$1021
  Aftermarket price range: $200-$500

Related Codes That Often Appear With This One

• P0203 — As per Mazda TSB #01-017/16, an internal PCM failure often causes injector circuit faults for cylinders 2 and 3 to be stored together. This is the strongest indicator that the PCM is the root cause.
• P0302 — This code indicates a misfire on cylinder 2. Since P0202 means the injector isn't firing correctly, the cylinder will not get the proper amount of fuel and will misfire as a direct result. P0202 is the cause, and P0302 is the effect.

Technical Service Bulletins (TSBs) & Recalls

• 01-017/16 (supersedes 01-004/17): Multi-Model - engine runs rough and check engine light on with DTCS P0201 and P0204 or P0202 and P0203. Identifies DENSO PCM internal failure as the cause.

Platform-Specific Known Issues

• Mazda Technical Service Bulletin #01-017/16 (which supersedes #01-004/17) notes that some 2014-2016 Mazda6 vehicles built before May 23, 2016 may experience a rough running engine with DTCs P0202 and P0203 stored together. This is often caused by an internal failure of the DENSO-produced PCM.
• A real-world repair story from a Mazda6 forum member involved a dealer quoting £1200 for a PCM replacement. The owner sourced a used PCM from a scrapyard and had the dealer reprogram it, bringing the total cost down to £400, which successfully fixed the issue.

Mechanic-Grade Diagnostic Values

• Fuel Injector Coil Resistance — expected: 1.6–2.52 Ω (at 0—80 °C / 32—176 °F). Failure: A reading of 0 Ω (short) or infinite/OL (open) indicates a faulty injector.
• Injector Pulse Width (Live Scan Data) — expected: ~1–8 ms at idle, increasing with engine load.. Failure: No pulse or an erratic pulse width on cylinder 2 compared to other cylinders.
• Injector Connector Voltage (Key On, Engine Off) — expected: Approximately 12V (battery voltage) on the power supply pin.. Failure: Low or no voltage indicates a problem with the power supply circuit, fuse, or relay.

Scan Tool Commands That Help

• Mazda IDS or advanced bidirectional scanner (e.g., iCarsoft, Autel): Injector Circuit Test / Active Test — This function allows manual activation of the cylinder 2 injector to see if it responds ('clicks'). It helps definitively separate a failed injector from a wiring or PCM driver problem. If the injector clicks during the test but not when the engine is running, the issue is less likely to be the injector itself.

Wiring & Ground Locations

• Engine Ground (General) — A key ground point is located on the passenger side motor mount. Another is near the High Pressure Fuel Pump (HPFP). A main chassis ground is located under the driver's side headlight area.. The PCM relies on solid ground connections to accurately control the injector driver circuits. A poor or corroded engine ground can introduce electrical noise or voltage drops, potentially causing the PCM to misinterpret the injector circuit's status and trigger a P0202 code. One owner with injector voltage issues traced the problem to the PCM not sending a ground signal to the injector relay.
• Injector #2 PCM Pins — The two wires for the cylinder 2 injector run from the injector connector directly to specific pins on the Powertrain Control Module (PCM) connector.. To rule out a wiring issue, a continuity test must be performed on both wires between the injector connector and the corresponding PCM connector pins. This confirms there are no breaks (open circuit) or shorts to ground in the harness.

Real Owner Repair Stories

• Mazdas247 Forum user 'beefski' (2013 Mazda CX-9 (similar engine family principles)) — P0202 error code.
  ❌ Tried (didn't work) Initial diagnosis pointed towards injector, wiring, or PCM as is typical for P0202.
  ✅ What actually fixed it Replacing the coil pack and spark plug for cylinder 2 resolved the P0202 code. This is unusual, as a P0302 (misfire) would be the expected code, but it highlights that sometimes underlying ignition issues can be misinterpreted by the PCM as a circuit fault.
• Mazdaspeeds.org Forum user 'Rogi' (2007 Mazdaspeed 6 (different engine, but demonstrates a universal electrical principle)) — No voltage to injectors after an engine install.
  ❌ Tried (didn't work) Checking multiple known ground points in the engine bay (passenger motor mount, starter ground, HPFP ground, driver headlight area).
  ✅ What actually fixed it The user discovered the PCM was not sending a ground signal to the main injector relay. By running a temporary ground wire to the relay, the injector control module activated and the car started. This confirmed the root cause was a fault in the PCM's ability to ground the relay, not the injectors or their individual wiring.

OEM Part Supersession History

• PY01-13-250 → PY01-13-250 — No supersession found. This part number remains the current OEM part for the specified vehicle range.
  Heads up: Aftermarket injectors may have different flow rates or atomization patterns. It is recommended to replace all four injectors as a set if using aftermarket parts to ensure balanced engine performance.

Model Year Variations Within This Range

• 2014 - May 23, 2016: Vehicles built before May 23, 2016, with VINs lower than JM1GJ**484154 are subject to TSB #01-017/16, which identifies an internal PCM failure as a likely cause for P0202, especially when paired with P0203. Vehicles built after this date have an updated PCM where this specific fault was corrected.