What Causes the Engine Warning Light to Illuminate and Transmission Jerking?

[ArthurLynn]

Engine warning light illumination and transmission jerking are related to sludge in the transmission and reduced air intake. Sludge in transmission fluid: When sludge circulates within the transmission fluid and blocks oil passages in the valve body, it can cause jerking issues. Prolonged exposure to this condition may lead to a series of transmission problems such as overheating, harsh shifting, and slippage. Solution: Wait for carbon deposits to be flushed out, and it's recommended to promptly inspect engine carbon buildup and clean if necessary. Reduced air intake: Engine ignition, air intake, and fuel injection collectively determine fuel combustion, which is the power source of the engine. If air intake decreases, ignition weakens, or fuel injection reduces, power output becomes insufficient, resulting in jerking sensations. The solution is to avoid frequent gear shifts that affect engine RPM.

[AnastasiaFitz]

I've encountered many such issues where the engine warning light comes on accompanied by transmission jerking, often due to a chain reaction across several systems. The most common cause is problems with the engine ignition system—worn spark plugs or leaking ignition coils lead to unstable engine power output, which naturally results in rough gear shifts. It could also be a faulty crankshaft position sensor sending incorrect signals to the ECU, causing erratic shift commands. Sometimes, degraded transmission fluid or a clogged filter causes unstable oil pressure, leading to jerking. These situations shouldn't be ignored—it's best to immediately read the fault codes to pinpoint the issue. Replace sensors if needed or clean the oil passages; delaying repairs too long may damage clutch plates. Don't skip regular maintenance—periodic checks on spark plugs and transmission fluid can prevent such problems.

[JulianaMarie]

Last time I helped a friend check his old car, we encountered the same issue—the engine light was on, and there were jerky gear shifts. We found it was mainly an electrical problem, such as loose sensor connectors causing signal interruptions. The computer thought there was an engine issue and turned on the light while sending incorrect commands to the transmission. Another possibility was poor grounding contact, leading to unstable voltage affecting the control module. It’s recommended to first check the battery terminals and wiring harness connections, clean any oxidation, and re-tighten them. A stuck solenoid valve in the transmission valve body can also cause both the light and jerking—try adding a bottle of cleaner. Of course, the most reliable approach is to use a diagnostic tool to read the specific fault codes, making it clear whether it’s transmission slippage or engine misfire. When repairing, remember to use OEM sensors, as aftermarket parts often have poor compatibility and can lead to recurring issues.

[Bryce]

This combination of faults is usually internally related. Abnormal engine combustion, such as excessive carbon buildup, triggers the malfunction indicator lamp when the computer detects abnormal emissions, while unstable power output affects gear shifting. On the transmission side, excessive clutch wear or blocked valve body oil passages can cause jerky shifts due to unnatural power transfer during gear changes. There could also be a communication fault between the two control modules, requiring inspection of the OBD interface and data lines. It is recommended to immediately read the fault codes to pinpoint the issue, prioritizing checking the transmission fluid level and color for any metal debris. Even a simple short circuit in the oil temperature sensor can lead to a chain of faults. For safety, avoid sudden acceleration and drive at low speeds to a professional repair shop for inspection.