P0705 Fault Code

Long Description

Fault code P0705 is logged when the vehicle’s primary computer, the powertrain control module (PCM), has detected an issue with the transmission range sensor.

This happens when the PCM is either receiving no signal or an erroneous signal from the transmission range sensor. This means the PCM cannot determine what gear the vehicle is currently in.

The transmission range sensor, also called the neutral safety switch, has the vital role of informing the PCM that the vehicle is in fact in neutral or in park, as well as what gear it is in when driving. Without this, many vehicles will be unable to start.

This code is obviously limited to vehicles with automatic transmissions as the driver plays the role of the PCM in this instance with a manual transmission.

Both Kia and Hyundai automatic transmissions are fairly susceptible to this fault code. Mercedes-Benz is another manufacturer that is commonly searched with this code.

Other Signs of This Problem

There are a number of noticeable signs of this issue as it can strongly impact the driveability of the vehicle.

The most obvious sign of this issue is the Check Engine light being illuminated.

In some vehicles, the vehicle will not be able to start either. This can be different with certain vehicles starting in gear. In first or reverse, this will be the car will lunge forward or backward when starting.

These signs continue to the driving of the vehicle as well. Gear changes can be delayed and harsh.

Electronics like the gear display and reverse lights will also behave erratically in many instances,

There may be other similar fault codes logged as well. These can be P0706, P0707, P0708, and P0709.

What Could Be The Problem?

The causes for this fault code will typically be found within the transmission range sensor circuit or the transmission system.

It is possible for a faulty transmission sensor to send the incorrect or no signal to the PCM. This can be a result of defects or damage. Additionally, the transmission sensor circuit could have a short or open circuit condition due to frayed wires or loose connections.

A defective shift linkage can also cause this issue as it does not properly link the gearshift and gears.

A defective valve body is another potential cause for this issue.

As with all fault codes, it is possible for the PCM to be defective or running on outdated software.

Fixes

There are various fixes that can be taken, depending on the issue at hand.

One of the most likely fixes is to repair any damaged wires or loose connections in the transmission sensor circuit.

Additionally, a faulty transmission sensor should be replaced.

A damaged or faulty shift linkage needs to be replaced.

Any defects in the valve body need to be repaired or replaced.

In rare cases, the PCM will need to be replaced. It is also possible simply requires a software update.

Seriousness

Fault code P0705 should be considered a moderately serious problem. At best, it will hamper the driveability of the vehicle significantly, but there is no major risk of damage to the components for short time periods.

However, it may render the vehicle undrivable if there is a no-start condition.

It is best to have this issue fixed as soon as possible to ensure normal driveability.