P0689 OBD-II Trouble Code: ECM/PCM Power Relay Sense Circuit Low

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0689 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0689 code

P0689 is a diagnostic trouble code (DTC) for "ECM/PCM Power Relay Sense Circuit Low". 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 $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 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$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0689 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0689 code definition

Whenever the Powertrain Control Module (PCM), or Engine Control Module in some vehicles, detects an abnormal voltage reading coming from the relay control circuit that supplies its power, a P0689 trouble code is stored. In addition, the Check Engine Light also illuminates. Related trouble codes that can also be stored with a P0689 trouble code include P0685, P0686, P0687, P0688, and P0690 codes.

What the P0689 code means

A P0689 trouble code signifies that the relay control switch to the PCM is sending a voltage signal that is out of the range of manufacturer specifications. While the storage of this code also leads to the illumination of the Check Engine Light, some vehicle makes and models require multiple ignition cycle with such a failure taking place before the Check Engine Light illuminates.

What causes the P0689 code?

A faulty PCM relay is the most common reason for the storage of a P0689 trouble code. Some other common causes include:

  • a defective PCM,
  • bad battery, corroded or damaged battery cables or cable ends
  • shorted or open circuits, a bad fusible link, or a blown fuse

What are the symptoms of the P0689 code?

Various symptoms can come about due to P0689 trouble code and range from just the illumination of the Check Engine Light to the vehicle not starting at all. The mechanic should keep in mind that if the PCM relay is defective that the Check Engine Light might not come on at all.

How does a mechanic diagnose the P0689 code?

While a P0689 trouble code is most commonly caused by a faulty ECM/PCM power relay sense circuit, a mechanic should fully diagnose the system to make sure another component, such as the PCM itself, is not at fault. To diagnose a P0689 trouble code requires the use of an advanced scanner, manufacturer's wiring schematic, and a digital volt/ohmmeter. The mechanic must also perform the following diagnostic steps:

  • Begin by inspecting the battery, battery cables, and battery cable ends.

  • Test the fuses and fusible link for fault.

  • Using the manufacturer's wiring schematic, carefully inspect all wiring, connectors, and components dealing with the PCM.

  • Clear the code and test the system to see if it returns, making sure to test drive the vehicle.

  • If the code returns or the vehicle does not start, unplug the PCM relay connector and test for reference voltage and ground signals, comparing them to the manufacturer's specifications.

  • The mechanic should make sure to unplug the PCM and all other related modules before probing the circuits to avoid damage and control module memory loss.

  • Inspect the PCM to make sure it is not faulty.

*Clear the trouble code before retesting the system to see if the code returns.

Common mistakes when diagnosing the P0689 code

A common mistake made by mechanics when diagnosing a P0689 trouble code is to replace the PCM when it is in fact not faulty. This is an unnecessary repair/replacement that results in the return of the trouble code because the relay, which is actually at fault, still remains.

How serious is the P0689 code?

If left unfixed, the problems associated with a P0689 trouble code can lead to the vehicle not starting. The Check Engine light can also fail to illuminate when the PCM stores a P0689 trouble code due to a fault in the PCM.

What repairs can fix the P0689 code?

To repair a P0689 trouble code, the mechanic should perform the following:

Additional comments for consideration regarding the P0689 code

The mechanic needs to keep in mind that a P0689 trouble code only comes about in older vehicles that are equipped with a relay to provide power to the PCM, as opposed to a fused wire directly from the ignition switch to the battery junction box to supply power to the PCM.

Need help with a P0689 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.

trouble codes
Check Engine Light
P0689

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0689 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,578

Rating Summary
3,265
157
41
23
92
3,265
157
41
23
92

Aaron

7 years of experience
71 reviews
Aaron
7 years of experience
Aaron showed up a little early and got right down to work. He was very knowledgeable and kept me informed of everything he was doing. A friendly and capable mechanic.
2005 DODGE GRAND CARAVAN - CHECK ENGINE LIGHT IS ON - AUSTIN, TEXAS

Theodore

13 years of experience
814 reviews
Theodore
13 years of experience
Very quick and Nice to chat with.
2003 AUDI A4 QUATTRO - CHECK ENGINE LIGHT IS ON - SEATTLE, WASHINGTON

Oliver

10 years of experience
30 reviews
Oliver
10 years of experience
Very nice and helpful!
2006 NISSAN SENTRA - CHECK ENGINE LIGHT IS ON - VIRGINIA BEACH, VIRGINIA

Tien

20 years of experience
746 reviews
Tien
20 years of experience
So far I think the service is great.
2007 FORD FUSION - CHECK ENGINE LIGHT IS ON - HAYWARD, CALIFORNIA

More related articles

How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...

Related questions

Q: Code p0010 camshaft actuator comes up, and mis fires. Just replaced intake manifold and these weren't issues before that.

Hi there. There are a few possibilities here. It is possible that you had a valve timing issue prior to working on the manifold. These engines have a ton of issues with the balance shaft and the valve timing as...

Q: Car was working fine then randomly shut off and will not turn back on, check engine light came on after the car turned off.

Hi there. First you would need to check for any codes that could be stored or pending on the ECM (computer). The code will direct you to the location area that could be the cause of the noise that occurred...

Q: Is there a way to check my computer to see if it's faulty or not?

Your computer is located inside the car and would need to be tested by scanning the computer to see if it is storing fault codes for an internal problem or an indication to some engine sensors that may have been...

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.

1-800-701-6230 · hi@yourmechanic.com