The P0935 code is a diagnostic trouble code (DTC) that indicates a problem with the hydraulic pressure sensor circuit in the transmission system. This code can affect the performance and drivability of your vehicle, as well as cause damage to the transmission components. In this article, we will explain what the P0935 code means, what causes it, what symptoms it produces, and how to diagnose and repair it.
What is the P0935 Code?
The P0935 code is a generic powertrain code that can be stored in most modern vehicles. It means that the transmission control module (TCM) has detected a high voltage signal from the line pressure sensor (LPS), which measures the hydraulic pressure in the transmission fluid. The TCM uses the LPS signal to regulate the pressure control solenoid (PCS), which controls the fluid pressure to the clutches and bands in the transmission. The desired line pressure is continuously compared to the actual line pressure and adjusted accordingly by the TCM.
If the LPS signal is higher than the expected range, the TCM will set the P0935 code and illuminate the check engine light. The TCM may also activate the limp mode, which limits the vehicle speed and gear selection to prevent further damage to the transmission.
What Causes the P0935 Code?
There are several possible causes for the P0935 code, such as:
- A faulty LPS
- A faulty PCS
- A shorted or open LPS circuit
- A shorted or open PCS circuit
- A poor electrical connection in the LPS or PCS circuit
- Low or dirty transmission fluid
- A clogged or restricted transmission filter
- A mechanical problem in the transmission, such as a worn or damaged clutch, band, valve body, or pump
What are the Symptoms of the P0935 Code?
The P0935 code can cause various symptoms, such as:
- Check engine light on
- Limp mode activated
- Delayed or harsh shifts
- Slipping or shuddering transmission
- Reduced fuel economy
- Transmission fluid leaks
How to Diagnose the P0935 Code?
To diagnose the P0935 code, you will need a scan tool, a digital multimeter, and a repair manual for your vehicle. The following steps are a general guide, but you should always follow the manufacturer’s recommendations for your specific vehicle model and year.
- Scan the vehicle for codes and note the freeze frame data, which records the engine and transmission conditions when the code was set. This can help you identify the possible cause and the frequency of the problem.
- Clear the codes and test drive the vehicle to see if the code returns. If the code does not return, it may have been an intermittent issue or a false positive. If the code returns, proceed to the next step.
- Check the transmission fluid level and condition. Low or dirty fluid can cause low pressure and poor lubrication in the transmission. If the fluid is low, top it up with the correct type and amount. If the fluid is dirty, burnt, or contaminated, flush and replace it with fresh fluid. Also, inspect the fluid for metal shavings or debris, which can indicate internal damage in the transmission. If the fluid is in good condition, proceed to the next step.
- Check the transmission filter for clogs or restrictions. A clogged filter can reduce the fluid flow and pressure in the transmission. If the filter is dirty or damaged, replace it with a new one. If the filter is clean and intact, proceed to the next step.
- Inspect the wiring and connectors in the LPS and PCS circuits. Look for signs of corrosion, damage, or loose connections. Repair or replace any faulty wires or connectors as needed. If the wiring and connectors are in good condition, proceed to the next step.
- Test the LPS and PCS for resistance and voltage. Using the multimeter and the repair manual, measure the resistance and voltage of the LPS and PCS according to the specifications. If the LPS or PCS is out of range, replace it with a new one. If the LPS and PCS are within range, proceed to the next step.
- Test the LPS and PCS circuits for continuity and short circuits. Using the multimeter and the repair manual, check the continuity and short circuits of the LPS and PCS circuits between the TCM and the sensors. If there is an open or short circuit, locate and repair the source of the problem. If the circuits are intact, proceed to the next step.
- Check for any mechanical problems in the transmission. If all the electrical tests are normal, the problem may be caused by a mechanical issue in the transmission, such as a worn or damaged clutch, band, valve body, or pump. To confirm this, you will need to perform a pressure test on the transmission using a pressure gauge and the repair manual. Compare the actual pressure readings to the desired pressure readings and identify any discrepancies. If the pressure is too low or too high, you will need to inspect and repair the affected components in the transmission.
How to Repair the P0935 Code?
The repair for the P0935 code depends on the cause and the severity of the problem. Some common repairs are:
- Replacing the LPS
- Replacing the PCS
- Repairing or replacing the LPS or PCS circuit
- Replacing the transmission fluid and filter
- Repairing or replacing the transmission components