Main power relay contacts sticking or welded partly closed; Faulty relay coil control circuit, such as a short to voltage or a damaged wire between the relay and the control module; Corroded or loose relay socket terminals, or a poor connection in the relay fuse box; Another circuit back-feeding voltage to the control module supply after ignition off; Low battery voltage or poor earths affecting the control module's relay monitoring; Internal fault in the engine or powertrain control module.

P068B

ECM/PCM Power Relay De-Energized Performance - Too Late.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
8B: FaultThe specific fault in that area

What it means

P068B means the engine or powertrain control module has seen the main power relay switch off later than it expected after the ignition was turned off. The control module monitors the relay feed or the relay's feedback circuit, and when power stays present for longer than the calibrated delay it sets this fault. It points to a relay that is sticking or a fault in its control or feed circuit.

Symptoms

Malfunction indicator lamp on
Engine slow to shut down or control unit staying powered after ignition off
Battery going flat after the car has been left standing
Hard starting or intermittent no-start
Other stored fault codes relating to control module supply voltage

Possible causes

Main power relay contacts sticking or welded partly closedlikely
Faulty relay coil control circuit, such as a short to voltage or a damaged wire between the relay and the control modulelikely
Corroded or loose relay socket terminals, or a poor connection in the relay fuse boxpossible
Another circuit back-feeding voltage to the control module supply after ignition offpossible
Low battery voltage or poor earths affecting the control module's relay monitoringpossible
Internal fault in the engine or powertrain control modulerare

How to diagnose

Read all stored codes and the freeze frame data, and note whether other power supply or battery voltage codes are present.
Check the battery condition and charging voltage, and clean and tighten the battery terminals and main earths.
Inspect the main power relay, its socket and the fuse box for heat damage, corrosion, water ingress or bent terminals.
Swap the relay with a known good identical one if the wiring diagram confirms it is the same type, then retest.
Listen and measure at ignition off: check how long the relay stays energised and whether the relay feed stays live after the expected delay.
Test the relay control wire and the feedback wire for short to voltage, open circuit or high resistance using the wiring diagram for that model.
Check for aftermarket accessories or other circuits that could back-feed the control module supply.
If the wiring and relay are proven good, check for software updates or known faults for that model before suspecting the control module.

How to fix

Replace the main power relay if it is sticking or failing to release.
Repair or replace damaged wiring or connectors in the relay control, feed or feedback circuits.
Clean or replace corroded relay socket terminals or the affected fuse box section.
Remove or correct any fitted accessory or fault that is back-feeding the supply.
Restore battery health and earth connections, replacing the battery if it is weak.
Repair or replace the control module, or apply a manufacturer calibration update, only once the circuit is proven good and a fault is confirmed.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but fix it soon because a relay that does not release can flatten the battery or cause starting problems. Avoid long periods of the car standing until it is checked.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.