P0689 code meaning
ECM/PCM Power Relay Sense Circuit Low
Powertrain system Generic code P06xx codes Check engine light
What P0689 means
The engine module switches its main relay coil to ground (control circuit), reads the switched voltage back on a sense line and keeps the relay on briefly after ignition off to save learned values. P0689 means the sense voltage is too low although the relay is commanded on – the contact does not close or has high resistance, the sense line is open or grounded, or a fuse in the load circuit has blown. GM sets it at 5 V or less with more than 9 V supply in 5 of 6 samples at 1 s, lamp after two trips; GM Europe's V6 below 6 V for 1 s and the 2.0 L turbo below 5 V, both without the lamp. GM includes an open sense line here. Starting problems or stalling follow, and on Saab the throttle control, which uses this voltage, may go into limp mode.
P0689 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0689
- Check engine light (depending on the maker)
- Starting problems or no start
- Engine stalls or stumbles
- Possibly electronic throttle limp mode
Common causes of P0689
- Most likelyRelay contact burnt or not closing, relay faulty
- PossibleFuse in the relay load or sense path blown
- PossibleHigh resistance or corrosion in relay carrier, connector or wire
- Less likelyWeak battery
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
ECM power relayRelay control circuitEngine control module
What each part of P0689 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| 89 | The exact fault in that area. |
What to do next
- Note P0689 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0689
What does P0689 mean?
P0689 means "ECM/PCM Power Relay Sense Circuit Low". The engine module switches its main relay coil to ground (control circuit), reads the switched voltage back on a sense line and keeps the relay on briefly after ignition off to save learned values. It is a generic code, so it means the same on every make.
Is it safe to drive with P0689?
Drive gently and only to a workshop. With P0689 the car can go into limp mode (reduced power) to protect itself.
Will P0689 fail an emissions test?
Yes, it can. P0689 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0689 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0689 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.