(Image: https://g28carkeys.co.uk/wp-content/uploads/2023/10/chrome_trhg3QMQrz.png)How to Replace an audi a1 car key G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge over the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors in the right way.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain is stretched or a jump link on the upper chain of timing. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult since there are two pins for the connector and they have different functions but the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is fully functional, it should read about 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant decrease in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. When i crank the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline jump out but the 4th stay closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found zero ohm. Therefore, i think the issue is somewhere else.
(Image: https://g28carkeys.co.uk/wp-content/uploads/2023/11/happy-african-american-businessman-holding-car-key-2022-12-16-16-36-17-utc-min-scaled.jpg)I also tried to reset the PID without success. The car key cover Audi will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62), even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not sure what to do. I feel like i've pretty much eliminated everything else. However, i'm afraid that I may have missed something. If anyone has any ideas please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style sensor is the same as the G4 and both are used in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or from a parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black end of the connector). They must be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines needs to know the position and speed the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.
A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, or a misfire while in gear. If you experience any of these problems, it is likely your sensor is failing and should be replaced. The good news is that they are very affordable and easily accessible, especially in the case of the Bosch model, which is what we have. Alternately, the GM version of this unit is also a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of problems in your car. It's an essential component of the audi key fobs's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is turning. If this sensor fails, it could cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to control fuel, timig, and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a common feature across the audi q7 key 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU, so you might find some good ones in wrecking yards.