P1686 — Metering Oil Pump Malfunction

Meaning for brands

Chery

For Ford vehicles

metering oil pump stepping motor cont. circuit Mazda

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P1686 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the metering oil pump for damage, corrosion, chafing or poor contact.
Subsystem check Run the module's actuator test for the metering oil pump if your scanner supports it — a component that does not respond to a direct command is confirmed faulty.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1686 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1686 (parts and labor, USD, independent shop rates): Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000; Repair wiring or connectors: $80–$250. Overall, fixing P1686 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of P1686?

The most common causes are: open or shorted wiring in the circuit, corroded, loose or damaged connector, control module driver fault.

Will P1686 clear itself?

Sometimes P1686 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

Is it safe to drive with P1686?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

What are the symptoms of P1686?

Drivers most often notice: increased fuel consumption in some cases, possible limp mode depending on the affected component, Check Engine Light on, the affected system operates intermittently or not at all.

How much does it cost to fix P1686?

Replace the faulty sensor or actuator — $150–$500; Control module repair — $300–$1,000; Repair wiring or connectors — $80–$250. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

When your check engine light comes on and a scan tool reveals P1686, you're looking at a fault that lives in the powertrain control module's self-diagnostic system. The code translates to "Metering Oil Pump Malfunction," which means the module has detected that one or more circuits feeding the metering oil pump assembly aren't behaving within factory specifications. The engine computer runs a self-test on these circuits every time you start the car and periodically while driving; when live sensor readings or actuator feedback fall outside acceptable ranges, P1686 gets logged.

The metering oil pump in this context refers to a component that controls oil flow or pressure for a specific engine function—typically regulating oil delivery to variable valve timing actuators, turbocharger oil supply lines, or transmission cooling circuits depending on your vehicle's design. The control module watches both the command signal it sends out and the feedback it receives back. A discrepancy between what the module commanded and what the circuit reported back triggers the failure flag. Unlike straightforward open-circuit or short-circuit faults, P1686 can point to problems inside the component itself or within the module's internal driver circuitry, which means diagnosis requires a methodical approach rather than jumping straight to part replacement.

What makes P1686 particularly useful for diagnosis is the freeze frame data that accompanies it. When the fault occurs, the module saves a snapshot of engine operating conditions—RPM, load percentage, coolant temperature, and vehicle speed at that exact moment. Technicians use this snapshot to recreate the failure conditions during testing, which dramatically increases the chance of catching an intermittent problem.

Symptoms

P1686 rarely announces itself with dramatic engine failures. The most obvious sign is the illuminated check engine lamp on your dashboard. Beyond that, you might notice:

Fuel economy dropping noticeably compared to your normal driving pattern
The affected auxiliary system (such as variable valve timing or an oil-controlled transmission function) behaving erratically or shutting down entirely
In some vehicle applications, the engine entering limp-home mode with reduced power output
Intermittent operation where the system works fine one drive and fails the next
Unusual noises from the engine bay if the oil metering function is completely lost

Causes

The root causes break down into several categories, with wiring problems occurring most frequently:

Damaged, corroded, or loose electrical connectors at the metering oil pump or its control module
Wiring harness chafing, insulation breaks, or connector pins that have backed out of their housings
Blown fuses or fusible links that protect the metering oil pump circuit
Open circuits (broken wires) or shorted circuits (wire touching ground or another voltage source)
Internal mechanical or electrical failure of the metering oil pump itself
Faulty sensors or actuators that provide incorrect feedback to the control module
Control module software bugs or internal driver circuit failures
Poor electrical grounds causing signal noise or complete circuit failure

How to Diagnose P1686

Proper diagnosis follows a logical progression from simple checks to complex ones:

Connect an OBD2 scanner, record all stored codes, and save the freeze frame data associated with P1686. Note the exact operating conditions when the fault set—these become your test parameters.
Research whether your specific make and model has published technical service bulletins addressing P1686. Search using your VIN on the manufacturer website or the NHTSA database. Many issues have documented software updates or factory repair procedures that eliminate trial-and-error diagnosis.
Perform a thorough visual inspection of the wiring harness and connectors serving the metering oil pump. Look for damaged insulation, corrosion buildup, bent or pushed-out pins, and any signs of prior repairs that might have been done incorrectly.
If your scan tool supports bi-directional controls, run the actuator test for the metering oil pump circuit. A component that fails to respond to a direct command is confirmed defective and ready for replacement.
With the connector unplugged, measure reference voltage, ground circuit resistance, and signal wire continuity from the module to the component. All values should fall within specifications in your service manual.
Perform a wiggle test on the harness while monitoring live data from the sensor or actuator. Any signal dropout or fluctuation indicates a broken wire or intermittent connector contact.
Clear the code, then drive the vehicle through a complete drive cycle that reproduces the freeze frame conditions. If P1686 returns, the fault is confirmed and present. If not, you may have an intermittent condition that will require continued monitoring.

Repair Options and Costs

Repair costs vary widely depending on which component is actually at fault. Here are typical scenarios at independent shop labor rates:

Repair wiring issues or replace damaged connectors: $80–$250 for parts and labor combined
Replace a faulty sensor or actuator in the metering oil pump circuit: $150–$500 depending on the specific component and vehicle
Control module repair or replacement: $300–$1,000 when internal circuitry or software is at fault

Total Cost to Fix P1686

Expect to pay somewhere between $80 and $1,000 to resolve P1686 depending on the root cause. The majority of failures trace back to wiring problems or failed sensors—these represent the lower end of the cost spectrum. Control module issues are comparatively rare and sit at the expensive end. The single most important thing you can do is confirm the exact cause before purchasing parts. Swapping a $500 sensor when the real problem was a $30 connector is an expensive lesson in skipped diagnostics.

Can You Drive with P1686?

For most drivers, the vehicle remains operational when P1686 is active. You may experience reduced fuel economy, diminished performance if the system entered limp mode, or auxiliary functions that don't operate correctly. However, if the metering oil pump controls something critical to engine lubrication or transmission operation, continued driving carries risk of accelerated wear or sudden failure. If you notice stalling, no-start conditions, or warnings affecting braking and steering, treat the situation as urgent and have the vehicle transported to a shop rather than driving it.