How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 through a grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the position of the camshaft, in order to activate the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are different connector pins, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is operating at its maximum. If you're experiencing issues with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power as if the engine was running out of gas or the injectors are not firing at all. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was unclean. When I crank the engine, there are no sparks, I put a piece of tissue on top of each injector hole and the 3 that were drenched in gazoline jump out but the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I assume check here that the problem is somewhere else.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, i think i've pretty much ruled out everything else. I'm worried that i might have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or at a parts store. Testing them is easy - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines needs to know the position and speed of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will display codes that could cause an engine shut down.
A failing G28 sensor could result in an inaccurate speed counter for your audi car key gearbox, a gearbox that shifts more quickly than normal, and/or a misfire while in gear. If you have any of these issues, it is likely your sensor is failing and should be replaced. The good thing is that they are quite affordable and easy to find, especially in the case of a Bosch sensor, which is what we have. Alternately, GM's version this part would be an option.
5. Tachometer
A failing engine speed sensor could be the reason behind many issues in your car. It's an essential component of the transmission of your Audi since it sends information to the ECU on how fast or slowly the engine of the car is turning. This sensor could cause the transmission to fail and other car components audi replacement car keys to be affected.
The G5 engine speed sensor is situated on the outside of the transmission website just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU is then able to process this signal to regulate fuel, timig, and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a more info resistance of approximately 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.