P0845 on 2020-2021 Ford Escape: Wiring Harness Fault and Fixes

What's Unique About the 2020-2021 Ford ESCAPE

The 2020-2021 Ford Escape is prone to a specific wiring issue that triggers P0845 along with many other seemingly unrelated codes. Ford issued Technical Service Bulletins (SSM 50116 and SSM 50245) identifying that a wiring harness near the steering column can chafe against the steering shaft u-joint. This causes a short in the 5-volt reference (VREF) circuit that supplies power to numerous sensors, including the transmission pressure sensor. Therefore, the root cause is often in the vehicle's electrical system, not the transmission itself.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp) is on
• Wrench light may be illuminated on the dashboard
• Engine runs rough or stalls
• Harsh or erratic transmission shifting
• Transmission may be stuck in one gear (Limp Mode)
• Blown fuse (specifically fuse 44 in the engine bay fuse box)
• Multiple other warning lights or trouble codes present simultaneously (AWD, Pre-collision assist, etc.)
• Sudden loss of power while driving

Most Likely Causes

1. Chafed Wiring Harness at Steering Shaft 🔴 High Probability As documented in Ford TSBs SSM 50116 and SSM 50245, the 14290 engine harness is routed in a way that it can rub against the steering shaft u-joint. Turning the steering wheel causes friction that wears through the wire insulation, leading to a short circuit in the VREF line. This is a known design or assembly flaw.
   How to confirm: Visually inspect the wiring harness located directly above the steering shaft u-joint, near the upper brake pedal mount. Look for signs of rubbing, chafing, or exposed copper wires. The issue may only be apparent when the steering wheel is turned lock-to-lock, which triggers the short circuit.
   Typical fix: Repair the damaged wires using solder and heat-shrink tubing. Wrap the repaired section in anti-abrasion tape. Secure the repaired harness away from the steering shaft using zip ties or by installing a harness locator over the provided stud to prevent future contact.
   Est. part cost: $5-$20 for wire repair supplies

Rare But Worth Checking

• Faulty Transmission Fluid Pressure (TFP) Sensor 'B': If the wiring harness inspection reveals no damage, the sensor itself could have failed. This is much less common on this specific vehicle than the wiring issue. On other Ford models with the 8F35 transmission, this sensor (part number JM5P-9D290-AE) has been known to fail, but the wiring should always be checked first on an Escape.
• Low or Contaminated Transmission Fluid: Extremely low or sludgy fluid can cause erratic pressure readings. This is a basic maintenance check but is unlikely to be the root cause if the TSB symptoms are present.
• Faulty Powertrain Control Module (PCM): A PCM failure is very rare and should only be considered after all other possibilities, especially the TSB-documented wiring issue, have been thoroughly ruled out.
• Rodent Damage: Owners have reported issues with rodents chewing on the soy-based wire insulation used in modern Fords, which can cause shorts anywhere in the harness. While less specific than the TSB issue, it's a possibility if damage is found in other areas.

Diagnosis Steps

1. Scan for all DTCs. If P0845 is present with any of the codes listed in TSB SSM 50116 or SSM 50245 (like P06A7, P2122, P0340, etc.), immediately suspect the wiring harness issue.
2. Check fuse #44 in the engine compartment fuse box. If it is blown, it is a strong indicator of the short circuit described in the TSB.
3. Gain access to the area under the driver's side dashboard, above the pedals.
4. Locate the steering shaft u-joint and the wiring harness (part of the 14290 harness) that passes near it. The TSB specifies the location as 'directly above the steering shaft u-joint near the upper brake pedal mount'.
5. With a good light source, carefully inspect the entire length of the harness in that area for signs of chafing, rubbing, or bare wires. Have an assistant turn the steering wheel lock-to-lock to see if the harness makes contact, as this movement can trigger the short.
6. If damage is found, disconnect the battery.
7. Carefully repair the damaged wires. Solder and heat-shrink tubing are recommended for a permanent repair. Insulate each wire individually.
8. Wrap the repaired section in high-quality electrical tape or a protective anti-abrasion loom.
9. Secure the harness firmly away from the steering shaft. TSB SSM 50245 specifically mentions 'installing the harness locator over the stud already provided' to ensure it cannot make contact again. A small stud for this purpose exists near the contact point.
10. If no harness damage is found, proceed with standard diagnostics: check transmission fluid level and condition, test the TFP sensor circuit with a multimeter, and inspect the sensor and its connector.

Parts You'll Likely Need

• Wiring Repair Supplies — Needed to fix the chafed wires in the 14290 harness, which is the most common cause of this code. Includes solder, heat shrink, and anti-abrasion tape.
  OEM price range: $5-$20
  Aftermarket price range: $5-$20
• Engine Wiring Harness (Full Replacement) (OEM #Varies (e.g., PK9Z-14290-A)) — In cases of severe damage, or if a repair is not feasible, the entire harness may need replacement. This is very expensive and often on backorder. Repairing the existing harness is the preferred method.
  Trusted brands: Ford
  OEM price range: $1200+
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• P06A7 — Sensor Reference Voltage 'B' Circuit Range/Performance. This code directly indicates the VREF circuit problem described in TSB SSM 50116.
• P2122 — Throttle/Pedal Position Sensor/Switch 'D' Circuit Low. The accelerator pedal position sensor shares the same VREF circuit that is shorting out.
• P2127 — Throttle/Pedal Position Sensor/Switch 'E' Circuit Low. Another pedal position sensor circuit affected by the VREF short.
• P0340 — Camshaft Position Sensor 'A' Circuit. The camshaft sensor is another component that can be on the affected VREF circuit.
• P0840, P0842, P0847 — Other transmission fluid pressure sensor circuit codes that are listed alongside P0845 in the TSBs as potential results of the same VREF short.
• C0040 — Brake Pedal Switch 'A' Circuit. This code is also listed in TSB SSM 50245 as a possible related fault.
🎬 Watch this walkthrough for diagnosing AWD faults and related service codes.

Technical Service Bulletins (TSBs) & Recalls

• SSM 50116: Details the loss of VREF and blown fuse 44 caused by the 14290 harness contacting the steering shaft, listing P0845 as a possible resulting DTC. It explicitly states 'Rotation of the steering wheel will trigger the short circuit.'
• SSM 50245: Supersedes the previous TSB, adding more DTCs to the list of possible symptoms and providing a more specific repair instruction: 'secure the harness by installing the harness locator over the stud already provided.'

Platform-Specific Known Issues

• A known design/routing issue exists where the 14290 wiring harness can rub against the steering shaft u-joint, causing a short circuit that triggers P0845 and a host of other electrical codes. This is documented by Ford in TSB SSM 50116 and SSM 50245.
• An owner on Reddit with a 2020 Escape experienced multiple electrical issues, including a powertrain malfunction light, which were traced back to this exact wiring harness issue and resolved by the dealer under warranty.
• Another owner on a Ford forum described a complex set of symptoms including incorrect gear ratio codes and throttle input errors, which are consistent with the VREF short caused by a damaged harness.

Mechanic-Grade Diagnostic Values

• Sensor Reference Voltage (VREF) at any affected sensor connector (e.g., accelerator pedal, TFP sensor) with key-on, engine-off. — expected: 5 Volts DC. Failure: A reading of 0 Volts or significantly below 5 Volts indicates a short to ground in the VREF circuit, consistent with the TSB. Voltage may fluctuate when the steering wheel is turned.
• Voltage at TFP Sensor Signal Wire — expected: Between 0.5V and 4.5V, varying with transmission pressure.. Failure: A constant 0V or 5V reading, or a reading that does not change when it should, points to a circuit fault or a failed sensor. Given the known TSB, a 0V reading is likely caused by the VREF short.

Scan Tool Commands That Help

• Ford IDS (Integrated Diagnostic System): Self Test > All CMDTCs — To retrieve all continuous, on-demand, and pending diagnostic trouble codes from all modules. This is crucial for seeing the full picture of codes that accompany P0845, which confirms the TSB issue.
• Ford IDS (Integrated Diagnostic System): Datalogger > PID Data — To monitor live data from the Transmission Fluid Pressure (TFP) sensor, Accelerator Pedal Position (APP) sensor, and other VREF-dependent sensors. A technician can watch these values drop to zero or behave erratically while turning the steering wheel, confirming the short circuit in real-time.
• Ford IDS (Integrated Diagnostic System): Module Programming — If the PCM is ever replaced (a very rare last resort for this issue), the new module must be programmed to the vehicle using IDS to function correctly.

Wiring & Ground Locations

• 14290 Harness — The specific section of this engine harness is located under the driver's side dashboard, passing directly above the steering shaft universal joint near the upper brake pedal mount.. This is the exact harness identified in TSB SSM 50116 and SSM 50245 as the location of the chafe and short circuit that causes the P0845 code and related VREF faults.
• Harness Locator Stud — A small, pre-existing stud on the vehicle body near the steering shaft, intended as a mounting point for a harness locator clip.. TSB SSM 50245 explicitly instructs technicians to secure the repaired harness to this stud to prevent it from contacting the steering shaft again. Ensuring the harness is properly clipped here is the final step of the correct repair.
• Engine Bay Fuse Box - Fuse F44 — Located in the under-hood fuse box.. TSB SSM 50116 identifies that the short circuit in the 14290 harness will cause fuse F44 to blow. A blown F44 fuse is a primary indicator that this specific TSB applies.
• Wiring Diagram Cell 005 — This is a reference within the official Ford service manual's wiring diagrams.. TSB SSM 50116 directs technicians to refer to this specific section of the wiring diagram for information needed to properly repair the damaged wires in the 14290 harness.

Real Owner Repair Stories

• Reddit user post on r/lincolnmotorco (2022 Lincoln Corsair (platform mate to Escape)) — Vehicle threw multiple warnings including 'Parking Brake Fault' and a check engine light, particularly when the engine was under load (climbing a hill).
  ❌ Tried (didn't work) Initial diagnosis was inconclusive.
  ✅ What actually fixed it A technician found a section of the wiring harness and a connector had melted due to being routed too close to the exhaust pipe. The harness was repaired and rerouted, which resolved all symptoms. This highlights the platform's vulnerability to harness placement issues.

Model Year Variations Within This Range

• 2020 vs 2021: While the core mechanicals and the wiring harness chafe issue are identical, some minor changes were made between model years. For the SE trim, the 2020 model came standard with heated front seats, while this became part of an optional package in 2021. Climate controls and USB port locations also saw minor revisions. These changes do not affect the diagnosis or repair of code P0845.