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2006 Dodge Ram 5.7 Hemi Transmission Issue: P0700 and P1521 Codes Explained

Model: Unknown Fault Code: P0700 Posted: 2016-04-16 05:20

I was driving normally when suddenly the RPMs spiked dramatically and the gas pedal became completely unresponsive. When I tried shifting gears, there was no response—no forward movement in any gear. I used a scanner and found two diagnostic codes: P0700 (Transmission Control System Malfunction) and P1521 (Incorrect Motor Oil Type). I recently changed my engine oil one week ago using 5W-20 high-mileage oil, so I'm wondering if this could be related. The transmission fluid level is normal, and the last fluid change was about six months ago. My vehicle has 177,281 miles. Is my transmission damaged? Could a recent oil change have caused these issues? I’m concerned that a repair shop might sell me a new transmission without thoroughly diagnosing other potential problems. What should I expect if the transmission is indeed faulty?

Related fault codes
P0700
Comments (3)
Anonymous 2016-04-16 06:39

Could you please provide your vehicle's year, model, engine type, and any modifications? Additional details would help in offering a more accurate diagnosis.

Anonymous 2016-04-16 07:22

No modifications. This is a 2006 Dodge Ram with a 5.7L Hemi engine. The issue started during morning drives when I'd take my kids to school—after turning on the truck, the RPMs would stay high and the vehicle would slowly move but eventually catch up to speed without any noticeable hesitation or clunking. Later that day, while driving home at a steady 60 mph, the RPMs suddenly spiked uncontrollably. I had to coast to the side of the road. While in drive, the engine would rev violently with no response from the gas pedal. Attempting to shift gears did nothing—no forward movement in any gear, as if the vehicle were in neutral.

Anonymous 2016-04-16 07:50

The P1521 code and throttle unresponsiveness suggest possible issues related to oil type or sensor calibration. A quick review of technical service bulletins (TSBs) shows that some reflash procedures—such as TSB 18-008-08 and TSB 18-018-06—may resolve similar symptoms. However, the P0700 code typically requires knowing the specific transmission type to interpret accurately. It could indicate a power module issue or communication failure between the transmission control module and the vehicle's ECU. Remote start systems may also interfere with transmission operation. Please confirm your exact transmission model (e.g., 48RE, 46RE) so we can narrow down potential causes.