Code P0733, Car going into limp mode?

DANNYF623

MEMBER
2005 MITSUBISHI GALANT
3.8L
V6
AUTOMATIC
166,111 MILES

The car was running fine until this morning, it slipped into third gear and the neutral light started to blink. The transmission fluid looks to be at the appropriate level, had it changed about a month ago. Checked the A/T control relay and that’s working fine. The wiring looks ok, just dirty. Giving me the code P0733 on the reader. Could it be the TCM or is it more probable to be internal transmission issues?

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5 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

This is common when the input shaft speed sensor is going out, this will not leave a code, here is the location so you can change it out. Also here is more information on the code:

The P0733 trouble code in your 2005 Mitsubishi Galant indicates a problem with the third gear ratio in the automatic transmission. Specifically, it means that the Powertrain Control Module (PCM) has detected that the actual gear ratio in third gear does not match the expected ratio.

When the P0733 code is present, it could be due to various reasons, including:

Low Transmission Fluid: Insufficient transmission fluid can lead to improper gear shifting and result in gear ratio discrepancies.

Dirty or Contaminated Transmission Fluid: Contaminated fluid can affect the transmission's hydraulic circuits, causing shift issues.

Faulty Shift Solenoid: The shift solenoid is responsible for controlling the engagement of specific gears. A malfunctioning shift solenoid can cause incorrect gear ratios.

Transmission Mechanical Issues: Problems with the transmission's internal components, such as worn clutch packs or a faulty valve body, can lead to improper gear engagement.

Wiring or Connector Problems: Electrical issues in the transmission system, such as damaged wiring or faulty connectors, can affect the proper operation of the transmission.

PCM or TCM Malfunction: A problem with the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) can result in incorrect gear ratio detection.

Check out the images (below). Please let us know how it goes

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Saturday, July 22nd, 2023 AT 11:13 AM

DANNYF623

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4 POSTS

Thank you, I most certainly value your time taken to reply.

Unfortunately, this did not fix the problem. I switched out the input shaft sensor today and same thing happens. Goes into limp mode when attempting 3rd gear. Even in manual it will not go past 2nd.

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Sunday, July 23rd, 2023 AT 9:34 PM

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

Can I ask if the speedometer works? I have seen the PCM go out and cause this issue as well. FYI. If the transmission fluid is not burnt this can be the problem. You can send the PCM out to have it checked by searching Google or Ebay for a service that can help you. Check out the images (below). Please let us know how it goes.

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Monday, July 24th, 2023 AT 11:25 AM

DANNYF623

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4 POSTS

Thanks again Ken!

The speedometer fluctuates, sometimes I’m going about 55 MPH, but the speedometer reads 40 MPH, other times I’m stopped at a light and it reads 20 MPH. This picture below shows an example of it in park.

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Monday, July 24th, 2023 AT 4:06 PM

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

It sounds like the PCM, or instrument cluster is not working correctly, we better do a CAN scan, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Please go over these guides and get back to us.