P0885 — TCM Power Relay Control Circuit/Open

OBD2 code P0885 flags a problem with the sensor and actuator circuits (TCM power relay control circuit/open). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, control module driver fault.

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 P0885 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 TCM power relay control circuit/open for damage, corrosion, chafing or poor contact.
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 P0885 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0885 (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 P0885 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

How much does it cost to fix P0885?

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.

What does OBD2 code P0885 mean?

Is it safe to drive with P0885?

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 is the most common cause of P0885?

The most common causes are: blown fuse feeding the circuit, faulty sensor or actuator of the affected circuit, control module driver fault.

Will P0885 clear itself?

Sometimes P0885 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.

P0885 is a powertrain diagnostic trouble code that points to a problem with the Transmission Control Module power relay control circuit. Specifically, the TCM has detected an open condition or electrical fault in the circuit responsible for supplying power to the transmission control module. When the control unit sees that the voltage path to the TCM is interrupted or outside factory specifications, it flags this failure and illuminates the check engine light.

The TCM handles all transmission shifting logic, adjusting gear changes based on inputs from various sensors. For it to operate correctly, it needs a stable 12-volt power source and solid ground connections delivered through the power relay circuit. When that circuit opens—meaning the electrical flow is broken or disrupted—the TCM may lose power entirely or receive insufficient voltage. This causes the module to fall back on default programming, often triggering limp mode to protect the transmission from damage. Your vehicle's ECU also logs a freeze frame snapshot when P0885 sets, capturing engine speed, load, temperature and vehicle speed at the moment of failure—data that proves invaluable during diagnosis.

Common Symptoms of P0885

Transmission may enter failsafe or limp-home mode, restricting available gears
Shifting feels harsh, delayed, or erratic during normal driving
Check Engine Light or Transmission Warning Light stays illuminated
Fuel economy drops noticeably compared to normal driving patterns
Vehicle may stall or struggle to restart in severe cases
Certain transmission functions operate intermittently or stop responding entirely

What Causes P0885?

The root cause is almost always an electrical problem somewhere in the TCM power relay circuit. Here's what to check, starting with the most frequent offenders:

Blown fuse or fusible link feeding power to the TCM relay circuit
Loose, corroded, or damaged connector at the TCM or relay harness junction
Open or shorted wiring in the affected circuit from age, heat damage, or physical abrasion
Poor ground connection at the TCM mounting point or ground strap failure
Failed TCM power relay itself—not the transmission computer, but the relay component
Faulty sensor or actuator within the related transmission circuit triggering secondary code
Failed TCM driver circuit inside the transmission control module—an uncommon but possible culprit

How to Diagnose P0885

Follow this systematic approach to pinpoint the failure without replacing parts unnecessarily:

Connect an OBD2 scanner and confirm P0885 is stored. Record the freeze frame data—it tells you exactly what conditions were present when the fault occurred. This guides your inspection.
Check for related codes. Any P08xx codes in the same scan often reveal the primary failure. Also search NHTSA and your manufacturer's TSB database by model year for known P0885 campaigns or software updates.
Inspect the TCM power relay circuit visually. Pull connectors and examine for corrosion, bent pins, moisture intrusion, or signs of heat damage. Check the harness routing for chafing where it passes near sharp edges or hot components.
Test voltage and ground at the TCM connector using a multimeter. The module needs consistent battery voltage on the power feed and near-zero ohms to ground. Any deviation here points the diagnosis immediately.
Perform a wiggle test. With the scanner monitoring live data, physically manipulate the wiring harness and connectors while observing the signal. Dropouts or code reactivation confirm an intermittent wire break or loose terminal.
Clear the code and complete a full drive cycle including the specific conditions from the freeze frame. If P0885 does not return after several runs under load, the issue was likely temporary—a loose connection that needs securing rather than part replacement.

Repair Options for P0885

Wiring repair or connector replacement: $80–$250
Faulty sensor or actuator replacement: $150–$500
TCM power relay replacement: $200–$400
Control module repair or replacement: $300–$1,000

Total Cost to Fix P0885

Most shops charge $80–$150 labor per hour. Parts costs vary significantly depending on the diagnosis. The actual total typically falls between $80 and $1,000. A blown fuse or corroded connector on the low end costs just parts and minimal labor. TCM replacement or internal module repair represents the high end. Always verify the exact circuit failure with multimeter readings before committing to expensive component swaps—the relay itself costs under $50, but full module replacement is a different price tier entirely.

Can You Drive With P0885?

In most cases the vehicle remains drivable, though you may notice limited gear selection, sluggish acceleration, or a transmission stuck in third or fourth gear. If the transmission has gone into full limp mode, you can still drive cautiously to a repair facility—avoid highway speeds and heavy loads. Treat the issue as urgent if you experience stalling, failure to move, or dashboard warnings for brakes or steering, as these indicate broader electrical compromise beyond the transmission circuit alone.