C1238 — ABS Hydraulic Pressure Differential Switch Input Circuit Failure

Q: "Can I drive with this code?"

"It depends on the severity. If the vehicle runs normally, short trips are usually OK. If you notice performance issues, drivability problems, or warning lights beyond the check engine light, get it checked soon."

Q: "Will this code clear itself?"

"Some codes clear automatically after the underlying issue is fixed and several drive cycles pass. But the root cause must be addressed first."

Q: "How do I find the exact cause?"

"A code alone doesn't pinpoint the failed part. You need a diagnostic scan ($50-150 at most shops) that reads freeze frame data and live sensor readings to identify the specific component."

What Does C1238 Mean?

C1238 is a diagnostic trouble code indicating: ABS Hydraulic Pressure Differential Switch Input Circuit Failure. This code relates to the chassis system. It has been reported in NHTSA complaints across 1 different vehicle models.

Common Causes

🔍 Sensor or control module malfunction

Real Owner Reports

From NHTSA complaint database — actual owner descriptions.

"2009 TOYOTA COROLLA - JAPANESE BUILT ABS/BRAKE WARNING LIGHTS AT APPROXIMATELY 31,000 MILES. 1. DIAGNOSTIC COMPUTER INDICATES TROUBLE CODES C0210 (SPEED SENSOR FAILURE) AND C1238 (PLUG TO RIGHT REAR WHEEL ASSEMBLY). PLUG TO ABS SENSOR AND TERMINAL REPAIR KIT WORK AT 32, 126 MILES. 2. 2ND"
— Toyota Corolla owner, 11/21/2011

Source: NHTSA Complaints Database

Most Reported Vehicles for C1238

Based on NHTSA owner complaint data.

#	Vehicle	Reports
1	TOYOTA COROLLA

Frequently Asked Questions

Can I drive with this code?

It depends on the severity. If the vehicle runs normally, short trips are usually OK. If you notice performance issues, drivability problems, or warning lights beyond the check engine light, get it checked soon.

Will this code clear itself?

Some codes clear automatically after the underlying issue is fixed and several drive cycles pass. But the root cause must be addressed first.

How do I find the exact cause?

A code alone doesn't pinpoint the failed part. You need a diagnostic scan ($50-150 at most shops) that reads freeze frame data and live sensor readings to identify the specific component.

What To Do Next

Possible Fixes

🔧 Have the code scanned with a professional-grade scanner to read freeze frame data
🔧 Test the relevant sensor(s) with a multimeter before replacing
🔧 If DIY repair isn't feasible, get a diagnostic from a trusted mechanic ($50-150)

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

C1238: ABS Hydraulic Pressure Differential Switch Input Circuit Failure