P0780 on 2014-2021 Mazda CX-5: Shift Malfunction Causes and Fixes

What's Unique About the 2014-2021 Mazda CX-5

For the SKYACTIV-Drive automatic transmissions in this CX-5 generation, the P0780 code is frequently not a random failure but a known issue addressed by Mazda. Multiple Technical Service Bulletins (TSBs) have been released because contamination in the transmission fluid can cause internal oil pressure switches (A and/or B) to temporarily or permanently get stuck. Depending on the vehicle's VIN and manufacturing date, the fix may be a simple TCM software update to adjust sensor tolerances, or it may require replacing the switches themselves. This is a more specific and common root cause than the generic possibilities often listed for this code.

Diagnostic Flowchart

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

Generation note: The 2014-2021 year range covers the end of the first generation (KE, 2014-2016) and the beginning of the second generation (KF, 2017-2021). Both generations use a SKYACTIV-Drive 6-speed automatic transmission, and the relevant Technical Service Bulletins cover vehicles across both generations, indicating a shared potential issue.

Symptoms You May Notice

• Check Engine Light and/or AT (Automatic Transaxle) warning light are on.
• Harsh or erratic shifting.
• Transmission gets stuck in one gear or enters "limp mode".
• Delayed shifting.
• Transmission slipping between gears or feeling like it shifts into neutral.

Most Likely Causes

1. Sticking Internal Oil Pressure Switches & Outdated TCM Logic 🔴 High Probability → Shop Engine Oil Pressure Switch Mazda has identified that contamination in the transmission fluid can cause oil pressure switches A and/or B in the control valve body to temporarily or permanently get stuck. This sends incorrect data to the TCM, triggering the P0780 code and others. Mazda has issued multiple TSBs to address this with either a software update or parts replacement. The TSBs explicitly note that this procedure does not apply if the vehicle has a "delayed engagement" concern from Neutral to Drive.
   How to confirm: A Mazda dealer or qualified shop will check for related DTCs (P0842, P0847, P0872, P0877, P1738) and check the vehicle's VIN and model year against the applicable TSBs (e.g., 05-002/15, 05-004/18, 05-002/23). The TSB provides a flowchart to determine if a TCM reprogram or immediate parts replacement is the correct first step.
   Typical fix: For some vehicles (e.g., 2016-2017 & 2021 CX-5), the first step is reprogramming the TCM with updated software. For others (e.g., 2013-2015 & 2018-2020 CX-5), the procedure is to replace the faulty oil pressure switches (A and B) located on the transmission's valve body. A transmission fluid drain-and-fill or flush is typically performed at the same time. After the repair, an "Initial Learning Procedure" must be performed.
   Est. part cost: $100-$250 for the switches and fluid.
2. Low or Dirty Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly While not specific to the CX-5, low or degraded fluid is a universal cause of transmission problems. It can lead to poor hydraulic pressure, overheating, and increased contamination, which is the known trigger for the pressure switch issue in these vehicles.
   How to confirm: Check the transmission fluid level and condition. The fluid should be at the correct level, pinkish-red, and not smell burnt. Note: Many modern transmissions like this one do not have a traditional dipstick and require a specific procedure to check the fluid level.
   Typical fix: Perform a transmission fluid drain-and-fill or a full fluid exchange with the correct Mazda-specific ATF (Type FZ). A transmission flush was quoted at a dealer for around $270.
   Est. part cost: $70-$150 for fluid.
3. Faulty Shift Solenoid ⚪ Low Probability → Shop Transmission Valve Body
   How to confirm: A diagnostic scan tool capable of reading transmission data can be used to command individual solenoids and monitor their response. Resistance checks can also be performed on the solenoids.
   Typical fix: Replace the specific faulty shift solenoid within the valve body. This is a common misdiagnosis for this platform, as the pressure switches are the more likely culprit per Mazda TSBs.
   Est. part cost: $50-$150 per solenoid.

Rare But Worth Checking

• Internal Transmission Mechanical Failure: → Shop Transmission Assembly If the fluid is found to have significant metal shavings, it could indicate a more severe internal failure of clutches or other hard parts. This is often accompanied by the manufacturer-specific code P1738 (Automatic transaxle internal malfunction), though P1738 is also listed in the TSB for the less severe pressure switch issue.
• Wiring Harness Damage: Damage to the wiring between the TCM and the transmission can cause communication errors or faulty sensor readings. This is less common than internal component issues but should be checked, especially if work has recently been done on the vehicle.

Diagnosis Steps

1. Scan the Transmission Control Module (TCM) for all stored DTCs. Note any codes that appear alongside P0780, especially P0842, P0847, P0872, P0877, and P1738.
2. Check for any applicable Technical Service Bulletins (TSBs) for your vehicle's specific VIN and model year. Mazda has several TSBs (05-002/15, 05-004/18, 05-002/23) for this issue.
3. Follow the diagnostic flowchart in the most current TSB. For certain model years (e.g., 2016-2017, 2021 CX-5), the first step is to reprogram the TCM. For others (e.g., 2013-2015, 2018-2020 CX-5), the TSB directs to replace the oil pressure switches.
4. If TCM reprogramming is indicated, have a Mazda dealer perform the update. One owner reported a cost of $170 for diagnosis and reprogramming.
5. If the TSB points to parts replacement, proceed with replacing oil pressure switches A and B on the valve body. This requires draining the fluid and removing the transmission oil pan.
6. Inspect the transmission fluid level and condition during the service. If significant foreign material is found in the oil pan, the oil strainer should also be replaced.
7. After the repair, perform the "Initial Learning Procedure" as specified by Mazda's service instructions.
8. Inspect the transmission wiring harness and connectors for any visible damage, corrosion, or loose connections, though this is a less likely cause.

Parts You'll Likely Need

• Transmission Oil Pressure Switch Kit (A and B) (OEM #FZ01-21-2C0) — This is the main hardware component identified in Mazda TSBs as the cause of the P0780 code due to sticking from contamination. It replaces the previous part number FZA1-21-2C0.
  Trusted brands: Mazda OE
  OEM price range: $90-$180
  Aftermarket price range: $70-$120
• Automatic Transmission Fluid (Mazda FZ) — Required when replacing internal transmission components or if the fluid is found to be low or dirty. A full fluid service is recommended during the repair.
  Trusted brands: Mazda OE, Idemitsu, Ravenol
  OEM price range: $20-$30 per quart
  Aftermarket price range: $15-$25 per quart

Related Codes That Often Appear With This One

• P0842 / P0847 — These codes relate to Oil Pressure Switches No. 1 & 2. They are frequently stored with P0780 and are a key indicator that the issue is related to the known TSB problem.
• P0872 / P0877 — These codes relate to Oil Pressure Switches No. 3 & 4 and are also listed in the same TSBs as P0780, pointing to a systemic pressure sensing issue.
• P1738 — This Mazda-specific code indicates a general 'Automatic Transaxle Internal Malfunction'. When it appears with P0780, it strongly reinforces the TSB-related diagnosis.

Technical Service Bulletins (TSBs) & Recalls

• 05-002-23: CHECK ENGINE LIGHT AND AUTOMATIC TRANSAXLE WARNING LIGHT ON with DTCs P0842, P0847, P0872, P0877, P0780, P1738

Platform-Specific Known Issues

• A known issue, documented in Mazda TSBs #05-002-23, #05-004/18, and #05-002/15, describes how contamination can cause internal oil pressure switches to stick, leading to P0780 and a host of other related codes.
• For some VIN ranges and model years, the problem is not the hardware but the TCM's sensitivity. A software update from Mazda can resolve the problem by adjusting the parameters for triggering the fault code.
• TSB 05-002/23 provides a specific flowchart for dealers: for 2013-2015 and 2018-2020 CX-5 models, the repair is to replace the switches. For 2016-2017 and 2021 models, the first step is to reprogram the TCM.

Mechanic-Grade Diagnostic Values

• Shift Solenoid Resistance (Off-vehicle) — expected: 1.0–4.2 ohms. Failure: Resistance outside of this range indicates a faulty solenoid.
• ATF Temperature for Initial Learning — expected: 40-110°C (104-230°F). Failure: The procedure will not run or will be inaccurate if the fluid is not within this temperature range.

Scan Tool Commands That Help

• Mazda M-MDS (IDS): Module Reprogramming — Used to update the TCM software as the first step for certain model years (2016-2017, 2021 CX-5) to fix the P0780 issue, per TSB 05-002-23.
• Mazda M-MDS (IDS): Initial Learning — This procedure is mandatory after replacing the oil pressure switches or the valve body to allow the TCM to relearn clutch engagement points and pressure timings. Failure to perform this can result in harsh shifting or other DTCs.
• Mazda M-MDS (IDS): Network Test — To verify communication with all modules on the CAN bus, including the TCM. This is a preliminary step to rule out broader network issues before focusing on the transmission itself.

Wiring & Ground Locations

• TCM Location — For the SKYACTIV-Drive transmissions in this generation, the Transmission Control Module (TCM) is typically located under the battery and battery box assembly, mounted on top of the transmission itself.. Access is required to inspect the TCM and its connectors for damage or corrosion. Removal of the battery and its tray is necessary to service or replace the TCM.
• Main Engine/Chassis Grounds — Several large ground cables are bolted to the chassis in the engine compartment and directly to the engine block. While specific diagrams are found in the service manual, these are the primary grounding points for the powertrain.. Although less common for this specific TSB-related issue, poor grounding can cause a wide range of electrical faults and erroneous sensor readings, which could theoretically trigger a shift malfunction code.

Real Owner Repair Stories

• Reddit user in /r/CX5 (2015 Mazda CX-5 Touring, FWD, ~100k miles) — Vehicle went into limp mode, CEL and A/T lights came on. Codes P0780 & P0847 were stored.
  ❌ Tried (didn't work) The user took the car directly to the dealer after pulling the codes.
  ✅ What actually fixed it The dealer performed a TCM reprogramming as per TSB 05-002/15. This was the only fix required. The user also opted for a transmission flush. Total cost was $170 for the diagnosis/reprogram and $269.95 for the flush.
• Mazdas247.com forum user (2014 Mazda CX-5) — CEL and AT lights on, codes P0847 and P0780 stored. Transmission would disengage while driving.
  ✅ What actually fixed it The dealership updated the TCM firmware based on a TSB. The user noted the update loosens the pressure sensor tolerances. The problem did not return after five months.
• Mazdas247.com forum user (2015 Mazda CX-5 GT AWD, ~10k miles) — Multiple dash lights (Engine, AT, TCS), codes P0847 and P0780.
  ❌ Tried (didn't work) Initially, there was confusion about parts availability.
  ✅ What actually fixed it The dealer replaced both valve body oil pressure switches as per TSB #05-005/14. The repair was covered under warranty.

OEM Part Supersession History

• FZA1-21-2C0 → FZ01-21-2C0 — This is the standard supersession for the oil pressure switch kit (A and B) used in the TSB repair. The new part number is the current replacement.

Model Year Variations Within This Range

• 2016-2017, 2021: Per TSB 05-002-23, the first step for these model years is to perform a TCM Reprogramming. The hardware (oil pressure switches) should only be replaced if the concern returns after the software update.
• 2013-2015, 2018-2020: Per TSB 05-002-23, the repair procedure for these model years is to proceed directly to replacing the oil pressure switches A and B. A TCM reprogram is not the primary fix.