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2018 Optima EX Transmission Jerky, P0700 Code - Limp Mode?

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Mike T. · rep 0 · May 25, 2:06 AM · 1 replies · solved · Question

Vehicle: 2018 Kia Optima EX

Hello forum,

My 2018 Kia Optima EX has been acting up lately. The transmission feels really jerky when shifting gears, especially from a stop or at lower speeds. Sometimes it feels like it's struggling to find the right gear, and a couple of times it's almost felt like it went into a 'limp mode' where it wouldn't shift past a certain gear.

The Check Engine Light is on, and my scanner shows a P0700 code, which I understand is a generic transmission control system malfunction code. I'm really worried this means a major transmission repair. Has anyone experienced this with their Optima?

What could be causing this, and what should I check first? I'm hoping it's not the worst-case scenario!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:06 AM

0

ClearTheCode admin answer:

The P0700 code is a general diagnostic trouble code indicating that the Transmission Control Module (TCM) has detected a malfunction within the transmission system and has illuminated the Check Engine Light. This code usually comes with other, more specific transmission-related codes stored in the TCM that your standard OBD-II scanner might not be able to read. The jerky shifts and potential 'limp mode' are classic symptoms of a transmission issue.

Here are the common causes and diagnostic steps:

  1. Check Transmission Fluid Level and Condition: This is the most crucial first step. Park on a level surface, warm up the engine, and check the transmission fluid according to your owner's manual (some Kias have sealed transmissions that require specific procedures). Low fluid can cause shifting problems. Also, note the fluid's color and smell; dark, burnt-smelling fluid indicates internal wear.
  2. Transmission Solenoids: Faulty shift solenoids within the transmission are a common cause of harsh or incorrect shifting. These solenoids control the flow of fluid to engage different gears. A specific code (e.g., P0750, P0755) would usually accompany P0700 if a solenoid is the issue.
  3. Transmission Speed Sensors: Input or output speed sensors can fail, causing the TCM to lose track of transmission speed, leading to incorrect shift points or limp mode. Again, more specific codes would likely be present.
  4. Wiring and Connectors: Inspect the wiring harness and connectors leading to the transmission and its sensors for any signs of damage, corrosion, or looseness.
  5. TCM Malfunction: While less common, the Transmission Control Module itself could be faulty, though usually, it's a component it controls that is the problem.

When to see a shop:

  • Immediately. Given the P0700 code and symptoms like jerky shifts and potential limp mode, it's highly recommended to have your vehicle inspected by a qualified mechanic or a transmission specialist as soon as possible. Driving with these symptoms can worsen the problem and lead to more expensive repairs.
  • A professional shop will have advanced diagnostic tools to read the specific transmission fault codes stored in the TCM (which are often manufacturer-specific and not generic OBD-II codes). They can accurately diagnose whether it's a fluid issue, a solenoid problem, a sensor failure, or a more serious internal transmission component failure. Do not delay, as transmission issues can escalate quickly.
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