P0700 on a 2017 Toyota Highlander
Transmission Control System Malfunction
P0700 on a 2017 Toyota Highlander indicates transmission control system malfunction. It usually stays drivable short-term but should be diagnosed promptly. The most common cause is low or burnt transmission fluid (typically $100–$350). Confirm the root cause before replacing parts.
What does P0700 mean on a 2017 Toyota Highlander?
P0700 is an "informational" code set by the engine control module when the transmission control module (TCM) reports any fault. P0700 itself does not identify a specific transmission problem — it is a flag that tells you to scan the TCM for the underlying code or codes. The actual fault could be anything from a shift solenoid failure to a slipping clutch pack to a low-fluid condition.
This guide covers P0700 across the 2015-2019 Toyota Highlander generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2015 through 2019.
Is it safe to drive a 2017 Toyota Highlander with P0700?
In most cases a 2017 Toyota Highlander stays drivable for short trips with P0700 active, but diagnose and repair it promptly. This is a high-severity code — ignoring it can lead to further damage or a failed emissions test.
What are the symptoms of P0700 on a 2017 Toyota Highlander?
- Check Engine Light is illuminated
- Transmission stuck in a single gear (often 3rd or 4th — "limp mode")
- Hard, delayed, or erratic shifts
- Torque converter clutch not locking up on the highway
- Higher than normal RPM at cruise
- Reduced fuel economy
- Possible transmission slipping under load
What causes P0700 on a 2017 Toyota Highlander?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Low or burnt transmission fluid Always check fluid level and condition first; many P0700s clear with a fluid and filter service. | Most common | $100–$350 |
| Failed shift solenoid (one or more) | Common | $250–$900 |
| Failed transmission speed sensor (input or output) | Common | $150–$500 |
| Worn or stuck valve body | Occasional | $600–$2,000 |
| Internal mechanical wear — slipping clutch packs or bands | Occasional | $2,500–$6,000 |
| Failed transmission control module (TCM) itself | Rare | $500–$1,500 |
| Wiring harness damage to TCM or solenoid pack | Occasional | $200–$700 |
How to diagnose this on a 2017 Toyota Highlander
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Scan the TCM for the specific transmission code
P0700 alone is not actionable. Use a scan tool capable of reading transmission codes (not just engine codes) to retrieve the actual P07XX, P08XX, or P09XX code that triggered the P0700. That code is what to act on.
Tools: Scan tool with TCM access
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Check fluid level, color, and smell
Most modern transmissions require checking fluid at operating temperature with the engine running and the selector in park or neutral, on a level surface. Dark, brown, or burnt-smelling fluid indicates clutch material in the fluid — fix the root cause; do not just refill.
Tools: Lift or jack and stands (sealed-for-life units), Vehicle-specific fluid spec
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Inspect the wiring at the transmission case
The external transmission harness is exposed to heat, oil, and road debris. Disconnect, inspect, and reconnect every external connector. A connector full of transmission fluid points to a leaking case seal that has wicked fluid up the harness — replace the seal and sometimes the harness.
Tools: Connector unlock tool, Electrical cleaner
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Pan-drop and inspect the filter and magnet
Drop the pan and inspect the filter, gasket sealing surface, and the magnet on the bottom of the pan. A magnet covered in fine metallic paste is normal. Large chunks of metal or clutch material indicate internal failure — at that point a teardown or replacement is required.
Tools: Drain pan, Socket set, New filter and gasket
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Verify TCM and ECM are talking on the CAN bus
Use the scan tool to read live data from both modules simultaneously. If the ECM sees a vehicle speed that disagrees with the TCM, suspect a speed sensor or harness fault. If the TCM is non-responsive, check power, ground, and CAN bus continuity to the module.
Tools: Scan tool with bi-module live data, Multimeter
NHTSA complaints & recalls for the 2017 Toyota Highlander
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2017 Toyota Highlander. Use these to gauge how common a problem is on your specific vehicle before you start chasing Toyota Highlander diagnostics.
- POWER TRAIN 68
- ENGINE 43
- UNKNOWN OR OTHER 49
- ELECTRICAL SYSTEM 46
- SERVICE BRAKES 29
4 active recalls
- ELECTRICAL SYSTEM Nov 2018
Fujian Wanda Automobile Glass Industry (Wanda) is recalling certain aftermarket Replacement Windshields sold for use in 2014-2018 Toyota Highlander vehicles. The windshields have an attached wire harness that water may leak into, possibly causing damage to the vehicle's Engine C…
NHTSA campaign 18E107000 - EQUIPMENT Aug 2017
Gulf States Toyota, Inc. (GST) is recalling certain 2017 Toyota Highlander and Highlander Hybrid vehicles equipped with accessory roof rail cross bars. The fasteners for the roof rails may not be torqued properly.…
NHTSA campaign 17V520000 - TIRES:TEMPORARY/EMERGENCY SPARE TIRE May 2017
Gulf States Toyota, Inc. (Gulf States) is recalling certain 2017 4Runner , 86, Avalon, Camry, Camry Hybrid, Corolla, Corolla iM, Highlander, Highlander Hybrid, Prius, Prius C, RAV4, RAV4 Hybrid, Sienna and Yaris vehicles. The spare tire air pressure was not adjusted to the prop…
NHTSA campaign 17V295000 - FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP Nov 2020
Toyota Motor Engineering & Manufacturing (Toyota) is recalling certain 2018-2019 4Runner, 2019-2020 Avalon, 2019 Corolla Hatchback, 2017-2019 Highlander, 2018-2020 Camry, 2020 Corolla, 2018-2019 Land Cruiser, 2017-2020 Tacoma, 2019-2020 RAV4, 2019-2020 Sequoia, 2017-2020 Sienna,…
NHTSA campaign 20V682000
How do I fix P0700 on a 2017 Toyota Highlander?
- Service the transmission fluid and filter to OEM specification
- Replace failed shift solenoid(s)
- Replace failed input or output speed sensor
- Replace or rebuild the valve body
- Replace the TCM
- Major rebuild or replacement of the transmission for internal failures
About the 2015-2019 Toyota Highlander
The 2015-2019 Toyota Highlander was commonly sold with the following powertrains: 3.5L V6, 2.4L Turbo I4, 2.5L Hybrid I4. Common trims include L, LE, XLE, XSE, Limited, Platinum.
Why P0700 by itself is not a diagnosis
P0700 is set in the ECM because the TCM reported a problem. The TCM stored the actual code. Many cheap OBD-II scanners only read engine codes — they will show P0700 with no further detail, leading to wasted parts swaps. A scan tool that can read transmission codes is essential for diagnosing P0700 efficiently.
P0700 with limp mode (stuck in one gear)
When the TCM detects a fault that could damage the transmission, it commands a default gear (often 3rd or 4th) and disables all shifting. This is “limp mode.” It is meant to let you drive a short distance to a shop, not for daily driving. Continuing to drive in limp mode for weeks can damage internal components even though the limp logic exists to prevent damage.
When to fluid-service vs rebuild
If the underlying transmission code is for a solenoid, sensor, or wiring issue and the fluid is clean, a fluid and filter service plus the failed electrical part is the right repair. If the underlying code is for ratio incorrect (P0731–P0734), torque converter clutch (P0741), or excessive clutch slip, the transmission has mechanical wear and a full rebuild or replacement is more cost-effective than chasing individual parts.