OBD-II trouble code
P0375: Timing Reference High Resolution Signal 'B' Malfunction
There is a second fine timing reference, and on many vehicles it is not a second sensor at all — it is a copy of the first one being passed between modules.
Quick facts
- System
- Powertrain
- Category
- Sensors / Timing
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $150 – $1,600
- DIY difficulty
- Advanced DIY
What does P0375 mean?
The useful question about P0375 is not what a high-resolution timing reference does — that ground is covered by the 'A' channel. The useful question is why a second one exists, because the answer decides what you are about to buy.
There are three architectures behind a 'B' reference and they are not variations on a theme. The first is a genuinely separate pickup, most common on engines where each cylinder bank has its own injection controller and each controller needs its own timing feed. The second is redundancy for the sake of checking: with two references the module can compare them against each other and work out that one of them is lying, which a single reference can never do. The third, and the one that catches people out, is a relayed copy. On a number of systems — heavy diesels in particular — the engine control module receives the crank signal, conditions it, and retransmits a duplicate to a separate fuel injection control module. The 'B' reference on those vehicles is that retransmitted copy.
If your vehicle uses the third arrangement, there is no sensor B to replace. Looking for one is the classic wasted afternoon on this code. The fault lives in the output stage of the sending module, in the wire that runs between the two modules, or in the input stage of the receiving module, and the repair is a wire, a connector, or a module with programming — never a pickup. Establishing which of the three architectures applies is therefore not preliminary work, it is the diagnosis.
The fact that a 'B' code has arrived while 'A' is healthy is itself informative, and it is evidence you only get on a two-reference vehicle. Everything the two channels share is working: the reference wheel is producing correct pulses, the crankshaft is turning as expected, the common supply and ground are intact. All of that is proven by the absence of an 'A' code, and it eliminates the most expensive possibilities before a single measurement is taken. What remains is the part of the path that belongs to 'B' alone.
The redundancy architecture explains something else that puzzles owners: a car can set this code and drive perfectly normally. If the module still has a trustworthy 'A' reference, it has what it needs to run the engine, and what it has lost is a cross-check. On a split-bank system the same fault is severe, because a controller with no reference cannot fire its injectors. Two identical codes, two entirely different days.
Common causes
- Failed output driver in the module that generates or relays the duplicated reference signal
- Open, shorted or chafed wire in the run between the sending module and the receiving module
- Corroded, backed-out or water-damaged terminal at either module connector
- Failed second pickup on engines where 'B' is a genuinely separate sensor
- Failed input circuit in the receiving module, commonly a fuel injection control module
- Poor or corroded ground at the receiving module leaving it without a stable reference to measure against
- Aftermarket tuning module or wiring spliced into the reference line between the two modules
- Incorrect or incomplete module programming after a replacement, leaving the two units expecting different signals
Symptoms
- Check engine light on with the engine running and driving entirely normally
- Hard starting, extended cranking or a no-start on split-bank injection systems
- Rough running or a dead cylinder bank where each bank has its own injection controller
- Reduced power as the module adopts a protected strategy after losing its cross-check
- Correlation or plausibility codes stored alongside this one
- Communication faults between the engine control module and the injection control module
Diagnostic steps
- 1.Identify the architecture before anything else. Find out from the wiring diagram whether 'B' is a second physical sensor, a redundant channel from the same sensor, or a copy retransmitted from one module to another. Everything downstream depends on this answer.
- 2.Confirm that no 'A' channel code is stored. A clean 'A' proves the reference wheel, the crankshaft and any shared supply are healthy, and removes the most expensive causes from the list at no cost.
- 3.If the diagram shows no second sensor, stop looking for one. The fault is a wire, a connector or a module, and hours can disappear searching for hardware that was never fitted.
- 4.Locate both ends of the reference run and check for previous splices, tuning modules or repairs. An interruption in that line is a common finding on the platforms that use this architecture.
- 5.Scope the signal at the sending module's output pin and again at the receiving module's input pin. A clean waveform leaving and a degraded one arriving isolates the fault to the run between them.
- 6.Test the receiving module's power and ground before condemning it. A module measuring a good signal against a bad ground reports a bad signal.
- 7.Check for communication codes between the two modules. A reference fault alongside a network fault usually means one connector, not two problems.
- 8.Where 'B' is a real second sensor, compare its output directly against 'A' on a two-channel scope. Two references from one engine must agree, and the one that disagrees is the one to replace.
Repair cost
$150 – $1,600
The architecture decides the bill. Where 'B' is a genuine second sensor, expect $40 to $200 in parts and $150 to $500 fitted, more if it sits on the harder-to-reach bank. Where 'B' is a relayed copy, there is no sensor to buy: a repair to the inter-module wiring or a connector is $150 to $500, and a failed sending or receiving module is $600 to $1,600 including programming. Diagnostic time is higher than average on this code because identifying the architecture is real work, commonly $120 to $250. Insist that the wiring diagram has been consulted before any module is ordered.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with crankshaft position sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.