P0798 OBD-II Trouble Code: Pressure Control Solenoid “C” Electrical

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0798 code

P0798 is a diagnostic trouble code (DTC) for "Pressure Control Solenoid “C” Electrical". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0798 DIAGNOSTIC Get a fair and transparent estimate upfront

A P0538 code indicates that the powertrain control module (PCM) has registered a problem related to an electronic pressure control solenoid or solenoid circuit.

What the P0798 Code Means

Computer controlled automatic transmissions actuate gear shifts and torque converter lockup via electronic pressure control solenoids. A P0798 code means that one of these solenoids is sending out readings that are out of parameters.

What causes a P0798 code?

  • Low transmission fluid level
  • Dirty or contaminated transmission fluid
  • Internal mechanical failures
  • Internal hydraulic passages blocked
  • Failed electronic pressure control solenoid
  • Failed PCM or transmission control module

What are the symptoms of a P0798 code?

  • Limp-in mode
  • Harsh shifts
  • Transmission slipping
  • Transmission overheating
  • Poor fuel economy
  • Failure of torque converter clutch to lock up or disengage
  • Disabled shifting – stuck in one gear
  • No detectable symptoms at all
  • Stored code and illuminated malfunction indicator lamp (MIL)

Other codes related to transmission slippage, gear ratios, torque converter clutch/lockup or shift solenoids may accompany this code.

How does a mechanic diagnose a P0798 code?

Ever since electronic automatic transmissions were introduced in the mid-1980s, vehicles have used a computerized control system that governs shifts based on information on vehicle speed, transmission output speed, engine load and engine/turbine speed. It determines shift points and the proper gear ratio for a given speed or engine load, optimizing engine performance and fuel economy.

The powertrain control module (PCM) uses this data to regulate transmission fluid pressure, via a high pressure pump (driven by the torque converter) and pressure control solenoids. The solenoids then govern the flow of fluid through the transmission’s internal hydraulic circuits. For a proper diagnosis, a technician will need a good quality scanner/code reader and a digital volt/ohmmeter (DVOM).

  • Any transmission diagnosis should start with an inspection of the transmission fluid on the dipstick. The fluid level should be within manufacturer’s recommendations and the fluid should be in good condition.

  • Fluid that smells burned is an indicator of transmission overheating, usually due to operation at a low fluid level. Internal mechanical failure may accompany burned fluid.

  • If fluid appears or smells burned, drop the transmission pan. Check for clutch material, metal shavings and other debris.

  • If debris is present in the transmission pan, a complete rebuild/fluid flush and new torque converter will likely be needed for the transmission to function properly.

  • If no debris is found in the pan, look closely for shorted or burned wiring or connectors in internal transmission wiring. Replace as needed. Most applications will require a full replacement of the internal transmission harness.

  • If the internal wiring, connectors and components all seem to be in good working order, connect the scanner to the diagnostic port and record any stored trouble codes. Freeze-frame the data.

  • Clear the codes and test drive the vehicle to see if codes return.

  • If codes don’t return, the problem may be an intermittent condition which may need to be allowed to worsen and return before a proper diagnosis can be made.

  • If transmission fluid is low, add fluid and find the source of a leak. Clean the bottom of the transmission, pan and crossmember using brake cleaner, then spray foot powder on the entire area to make it easier to track down the source and path of a leak.

  • If, after filling the transmission with the proper fluid, the code doesn’t return, it may have been caused by a low fluid level.

  • If the code returns and the transmission shows signs of slippage or delayed engagement, move on and check pump pressure using a manual pressure gauge.

  • Locate the appropriate port on the transmission housing and thread the end of the gauge to the port to record pump pressure. Compare your pump pressure readings with factory specs and repair accordingly.

  • Causes of low pump pressure can include a failed pump, clogged internal hydraulic passages, failed electronic pressure regulator or failed shift solenoids. Replacement of the pump will mean transmission removal and partial teardown.

  • If the transmission seems to operate normally but the code immediately returns, look for reference voltage and ground signals at the suspected pressure control solenoid.

  • Disconnect any related control modules from the circuit before checking circuit resistance, to ensure against damage.

  • Repair/replace any related systems circuits/connectors as needed. Retest the system to ensure that resistance and continuity are in line with factory specs. A manufacturer’s wiring diagram will be needed.

  • If all circuits are intact and resistance and continuity are within factory specs, connect the scanner and attempt to manually engage the electronic pressure control solenoid. If the solenoid will not actuate manually, replace the solenoid and retest the system.

  • If the control solenoid is good and all circuits are within factory spec, look for a defective high pressure pump, torque converter or PCM. Remember that PCM failure is rare.

Common mistakes while diagnosing P0798 code

In these instances, the electronic pressure control solenoid or wiring problems are often overlooked, with technicians going straight to the high pressure pump and replacing it in error.

How serious is a P0798 code?

A P0798 code can result in limp-in mode or a transmission that will not shift out of a given gear, and can lead to further problems.

What repairs can fix a P0798 code?

Addition comments for consideration for P0798 code

The parameters for setting a P0798 code can vary considerably from one manufacturer or even one model to another. Make sure you understand your vehicle’s make/model specs before going any farther.

Need help with a P0798 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
trouble codes
P0798

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0798 code.

SCHEDULE P0798 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


More related articles

P0501 OBD-II Trouble Code: Vehicle Speed Sensor Range/Performance
P0501 code definition Vehicle Speed Sensor Range/Performance What the P0501 code means P0501 is an OBD-II generic code that the engine control...
P0005 OBD-II Trouble Code: Fuel Shutoff Valve “A” Control Circuit/Open
P0005 P0005 code definition? Fuel Shutoff Valve “A” Control Circuit/Open What the P0005 code means P0005 is a generic type of of diagnostic trouble code which indicates that the Engine Control Module (ECM) detects a problem with the fuel pump...
P0705 OBD-II Trouble Code: Transmission Range Sensor Circuit Malfunction (PRNDL Input)
P0705 code definition Transmission Range Sensor Circuit Malfunction (PRNDL Input) What the P0705 code means Diagnostic trouble code P0705 indicates that the...

Related questions

Check Engine light came on
Multiple lights may be caused by multiple problems.Your BMW has a few dozen computers which can trigger warning lights to appear on your dash. Diagnosing multiple problems may be time extensive, but can be performed by a qualified technician with...
Check engine light stays on
Hello. In order to know why the light is on (https://www.yourmechanic.com/article/the-check-engine-light-demystified), I would need to know the codes from the computer. It can be anything for a computer issue to a bad gas cap. I usually scan the computer first...
Check engine light still on after repair. 2006 Infiniti G35
Hello. If the Check Engine Light remained on after the battery was plugged in, then it may be possible that the issue is with the wiring. Faulty wiring or a bad connector to the cam position sensor (https://www.yourmechanic.com/services/camshaft-position-sensor-replacement) keeping the...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com