P06A5 Sensor Reference Voltage “D” Circuit High
OBD-II Trouble Code Technical Description
Sensor Reference Voltage "D" Circuit High
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.
When faced with a stored P06A5 trouble code, I know from experience that the powertrain control module (PCM) has detected a high reference voltage condition for a particular sensor that has been given the label of "D" . I remember that the sensor in question has always been related to the automatic transmission, transfer case, or the front differential.
An additional sensor code will likely point me in the specific direction of the malfunction, with the P06A5 adding that sensor "D" reference circuit voltage is too high. To determine the sensor location (and function), as it regards the vehicle in question, I’d consult a reliable vehicle information source like All Data DIY. Should the P06A5 be stored alone, I would suspect that a PCM programming error has occurred. I always diagnose and repair any other sensor codes prior to diagnosing and repairing the P06A5 – keeping the higher than normal reference voltage condition in mind – because it will usually disappear once other (more specific) sensor codes are rectified.
I realize that the sensor in question is normally supplied with reference voltage signal (typically five-volts) via a switched (energized with the key on) circuit and a ground signal. Familiarity dictates that the sensor is going to be of either the variable resistance or electromagnetic variety and that it will complete the circuit in question. As a rule, sensor resistance should decrease as pressure, temperature, or speed is increased and vice versa. As the resistance level of the sensor changes (with varying conditions) and circuit voltage responds; the PCM recognizes the voltage variations as changes in pressure, temperature, or speed. If the input voltage signal, received by the PCM, is higher than a programmed limit, a P06A5 will be stored and a malfunction indicator lamp (MIL) may be illuminated. Some models will require multiple drive cycles (with a failure) for the MIL to be illuminated. Good things happen when I allow the PCM to enter readiness mode before considering any repair successful. I clear the code, after repairs are performed, and drive the vehicle normally (before handing it back over to the customer). If the PCM enters readiness mode, the repair was successful. If the code is reset, the PCM will not enter readiness mode and I know that a malfunction is still present.
Severity & Symptoms
The urgency of a stored P06A5 depends upon which sensor circuit is experiencing a high reference voltage condition. Accompanying codes must be considered before the degree of severity can be determined.
Symptoms of a P06A5 code may include:
Causes
Possible causes for this engine code include:
Diagnostic and Repair Procedures
Before beginning my diagnosis for a P06A5, I like to have a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source (like All Data DIY). I have also discovered that a portable oscilloscope can be helpful in this diagnosis.
I would start by consulting my vehicle information source to determine the location and function of the sensor, as it relates to the vehicle in question. I might continue by performing a visual inspection of sensor circuit related wiring harnesses and connectors. I’d repair or replace damaged or burned wiring, connectors, and components as required.
Next, I like to connect the scanner to the vehicle diagnostic port and retrieve all stored trouble codes and freeze frame data. I write the codes down, along with the order in which they were stored and any related freeze frame data, as this information may prove helpful if the code turns out to be intermittent. Now I would go ahead and clear the codes and test drive the vehicle to see if it is reset.
If the code is immediately reset, I would use the DVOM to test reference voltage and ground signals at the sensor in question. I would expect to find five-volts and a ground at the sensor connector.
I’d likely continue by testing sensor resistance and continuity levels, if the voltage and ground signals are present at the sensor connector. I can get the specs from my vehicle information source and compare my actual findings to them. Sensors that don’t comply with these specs will need to be replaced.
I always disconnect all related controllers from system circuits prior to testing resistance with the DVOM because I know that failure to do so may result in PCM damage. If reference voltage is high (at the sensor), use the DVOM to check circuit resistance and continuity between the sensor and the PCM. Replace shorted circuits as necessary.
If the sensor in question is electromagnetic with a reciprocating signal, use the oscilloscope to monitor live data. Focus on spikes, glitches, and maxed out circuits.
Additional diagnostic notes:
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"Delete Error Code Permanently, Disable DTC Error Code Function for p06a5 in the ECU"
In extreme cases, we even have the option to permanently remove the specific DTC p06a5 and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.
Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p06a5.
