C1704 — Right Rear Sensor Circuit Fault

chassis (brakes/steering/suspension)

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 C1704 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 C0xxx 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 right rear sensor circuit 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 C1704 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for C1704 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000. Overall, fixing C1704 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 do I diagnose C1704 myself?

Start with a scan: confirm C1704, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the right rear sensor circuit, and verify the suspect component against live data before buying parts.

Will C1704 clear itself?

Sometimes C1704 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.

How much does it cost to fix C1704?

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

What is the most common cause of C1704?

The most common causes are: control module driver fault, open or shorted wiring in the circuit, poor ground connection.

What are the symptoms of C1704?

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

When your scan tool pulls code C1704, the vehicle's control module is reporting a fault in the right rear sensor circuit. This places the problem squarely in the chassis systems — think brakes, suspension, steering sensors, or related actuators. The ECU constantly monitors the electrical behavior of these components: voltage levels, signal patterns, and ground integrity. When readings stray outside the factory-calibrated window, C1704 gets set and a snapshot of driving conditions is saved.

The module doesn't throw this code after a single bad reading. Most manufacturers require the anomaly to appear across multiple drive cycles before lighting up the dashboard. That freeze frame data — recorded the instant C1704 triggered — is gold for diagnosis. It captures engine speed, load, coolant temperature, and vehicle speed at the moment of failure. Pulling that data first tells you exactly what conditions to reproduce during testing, cutting hours off your troubleshooting time.

Common Symptoms

C1704 rarely shows up without company. Watch for these signals:

The right rear sensor system cuts out intermittently or stops working entirely
Check Engine Light or dedicated warning lamp illuminates on the dash
Fuel economy drops slightly in affected vehicles
Limp-home mode activates, restricting power or disabling certain辅助功能
ABS, traction control, or electronic stability systems may behave erratically
Unusual behavior from rear brakes, suspension leveling, or trailer brake controllers depending on vehicle application

Likely Causes

The fault almost always traces back to one of these culprits — start from the top:

Damaged wiring harness: chafed insulation, broken strands, or connectors rubbed through from road debris
Corrosion or moisture intrusion at the right rear sensor connector
Blown fuse protecting the affected circuit
Loose or unplugged sensor connection at the wheel well or rear body
Sensor or actuator failure from age, heat exposure, or physical damage
Control module internal driver fault (less common but possible on high-mileage vehicles)

How to Diagnose C1704

Follow this step-by-step approach to isolate the root cause without replacing parts you don't need:

Connect your OBD2 scanner — confirm C1704 is an active or pending code, not just a stale entry. Save the freeze frame data before clearing anything.
Check for related codes — C1700 through C1706 often appear together when a shared power supply or ground is the real problem. Also search your manufacturer's TSB database for service campaigns tied to this code family.
Inspect the right rear sensor area — locate the sensor (wheel speed, suspension position, brake pressure, or trailer接口 depending on your model). Pull the connector and look for bent pins, green corrosion, or melted plastic from overheating.
Test electrical integrity — with the connector unplugged, check reference voltage on the power pin, verify ground continuity on the ground pin, and confirm signal wire resistance matches spec. Most sensors want 5V reference and a variable signal or PWM output.
Wiggle test — reconnect everything, enter live data on the scanner, and physically work the wiring harness while monitoring the signal. Any dropout points to a broken wire inside the insulation.
Road test under freeze-frame conditions — clear the code, then drive the vehicle under the exact load, speed, and temperature conditions captured in the freeze frame. If C1704 returns, you've confirmed a hard failure.

Repair Options and Costs

Not every fix requires a parts cannon. Work through cheaper possibilities first:

Repair	Parts Cost	Labor	Total (USD)
Wiring repair or connector replacement	$20–$80	$60–$170	$80–$250
Replace faulty sensor or actuator	$80–$300	$70–$200	$150–$500
Control module diagnosis and repair	$200–$600	$100–$400	$300–$1,000

Most DIY mechanics tackle the wiring repair or sensor swap with basic hand tools and a multimeter. Control module work typically stays with professionals unless you have ECU programming experience.

How Much Should You Budget?

Expect to spend anywhere from $80 to $1,000 depending on what fails. The vast majority of C1704 cases resolve with a wiring fix or sensor replacement — well under $500 total at an independent shop. Control module replacement or bench repair sits at the high end and usually only comes into play after other causes are ruled out. Always diagnose before you buy parts — swapping sensors blindly wastes money when the real issue is a $15 connector or a pierced wire.

Can You Drive with C1704?

In most situations, the vehicle stays drivable. You might notice reduced performance, disabled辅助功能, or a mild limp mode. The urgency depends entirely on which subsystem the right rear sensor controls. If you see stalling, no-start conditions, or brake/steering warning lights alongside C1704, treat it as urgent — don't wait for a weekend project. Otherwise, schedule the repair within a week or two to prevent the fault from cascading into other chassis codes.