P0C27 — Auxiliary Transmission Fluid Pump Motor Current Low

OBD2 code P0C27 flags a problem with the automatic transmission control (auxiliary transmission fluid pump motor current low). Short, gentle driving to a shop is usually possible. Common culprits: valve body wear, internal mechanical wear (clutches, torque converter), faulty transmission speed sensor.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0C27 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 automatic transmission control for damage, corrosion, chafing or poor contact.
Subsystem check Check transmission fluid level and condition — dark, burnt fluid points to internal wear.
Subsystem check Read transmission-specific codes and live data (solenoid states, input/output speed) with a capable scanner.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0C27 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0C27 (parts and labor, USD, independent shop rates): Valve body repair or replacement: $700–$1,500; Transmission fluid service: $150–$350; Transmission rebuild or replacement: $2,500–$5,500; Replace a shift solenoid: $300–$800. Overall, fixing P0C27 usually costs between $150 and $5,500. 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 P0C27?

The most common causes are: valve body wear, internal mechanical wear (clutches, torque converter), faulty transmission speed sensor.

What does OBD2 code P0C27 mean?

Will P0C27 clear itself?

Sometimes P0C27 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 P0C27?

Drive only if the transmission still shifts predictably, and avoid highway speeds. Driving with slipping or limp mode accelerates internal wear — every kilometre can add to the final repair bill.

How much does it cost to fix P0C27?

Valve body repair or replacement — $700–$1,500; Transmission fluid service — $150–$350; Transmission rebuild or replacement — $2,500–$5,500; Replace a shift solenoid — $300–$800. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

The engine control module sets code P0C27 when it detects a problem with the automatic transmission's auxiliary fluid pump circuit. Put simply, the PCM has measured abnormally low electrical current flowing to the transmission's auxiliary pump motor. This diagnostic trouble code falls within the powertrain category, specifically addressing transmission control system performance. When your vehicle's computer notices this low-current condition persisting across multiple drive cycles, it stores the fault and illuminates the check engine light.

Modern automatics rely on consistent fluid pressure to maintain smooth operation. The auxiliary pump supplements the main pump during low-engine-RPM situations like parking maneuvers or heavy loads, ensuring fluid reaches critical components. When current to this pump drops below factory specifications, pressure regulation suffers, which directly affects shift quality and torque delivery. The PCM logs freeze frame data alongside P0C27 — this snapshot records engine RPM, load percentage, coolant temperature, and vehicle speed the instant the fault was detected. Technicians use this information to recreate the exact driving conditions where the problem surfaces.

Common Symptoms of P0C27

Illuminated Check Engine or transmission warning light on the dashboard
Noticeable gear slipping during acceleration or deceleration
Unusual shuddering or vibration felt through the vehicle body at highway speeds
Delayed or harsh gear engagement when shifting
Transmission stuck in a single gear with reduced power available — commonly called limp mode
Complete lack of forward or reverse movement in severe cases

What Causes This Fault Code?

Damaged or corroded wiring and connectors within the valve body harness assembly
Faulty transmission speed sensor providing inaccurate data to the control module
Worn or sticking valve body components affecting fluid regulation
Internal mechanical wear including damaged clutch plates or torque converter issues
Defective auxiliary transmission fluid pump motor itself
Low or contaminated transmission fluid restricting proper hydraulic function
Powertrain control module or transmission control module faults — less frequently involved

How to Diagnose P0C27

Connect a professional-grade OBD2 scanner, retrieve stored P0C27 data, and record all freeze frame information — this shows the precise operating conditions when the fault first appeared.
Scan for additional diagnostic trouble codes that may have triggered alongside P0C27. Related transmission codes often point directly toward the root cause. Check for manufacturer-specific technical service bulletins covering this code on nhtsa.gov or your vehicle brand's official service website.
Perform a thorough visual inspection of all wiring and electrical connectors related to the automatic transmission control system, paying special attention to areas near the valve body where chafing, heat damage, or moisture intrusion commonly occurs.
Inspect transmission fluid level and condition — healthy fluid appears red and transparent while dark, black, or burnt-smelling fluid indicates serious internal wear requiring immediate attention.
Access transmission-specific data through a capable diagnostic scanner, monitoring solenoid operation states, input and output shaft speeds, and hydraulic pressure readings in real time to identify circuit or mechanical deficiencies.
Clear the stored code and complete a controlled test drive that replicates the freeze frame conditions — observe whether P0C27 returns and under what circumstances.

Repair Options with Exact Costs

Shift solenoid replacement: $300–$800
Transmission fluid service including filter replacement: $150–$350
Valve body repair or complete replacement: **$700–$1,